SCIENCE:

A WEEKLY RECORD OF SCIENTIFIC

PROGRESS.

JOHN MICHELS, Editor.

PUBLISHED AT

229 BROADWAY, NEW YORK. P. O. Box 8838.

SATURDAY, JULY 31, 1880.

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PROFESSOR LEIDY'S "FRESH WATER RHIZOPODS OF NORTH AMERICA."

a

Dr. Leidy is acknowledged to be the highest authority on the subject treated in his great work, "Fresh Water Rhizopods of North America; " criticism of the book becomes, therefore, a work of supererogation, and we reserve to ourselves the more pleasing task of pointing out its many beauties and particularly its importance as one of the most valuable contributions to the literature of microscopic forms of life.

Published by the Department of the Interior of the United States Government, and forming volume twelve of the "Report of the United States Geological Survey of the Territories" in charge of Professor F. V. Hayden, it is produced in a sump

tuous form which no private publisher would have dared to imitate.

Dr. Leidy's Report covers about three hundred folio pages, illustrated by forty-eight full sized plates, printed in colors in the highest style of lithography.

It may be a superfluous question to most of our readers, but as Dr. Leidy himself inquires in the first page of his work, "What are Rhizods?" In reply he says, "Rhizopoda are the simplest and lowest forms of animal life, constituting the first class of the Protozoa. They derive their name from the Greek word rhiza, a root, and pous, a foot. They are mostly microscopic beings, although sometimes sufficiently large to appear as conspicuous objects." We may add that the essential characters are the gelatinous structureless bodies, and the locomotive organs consisting of variable retractile root like processes (pseudo-poda or false feet).

Their minuteness is compensated for by their multitude and wide-world distribution; essentially aquatic they occur wherever there is moisture; the search for them may be commenced in the crevices of the stones at your door step, and may be continued in every marsh, pool, ditch, pond, lake, sea and ocean, and from the greatest depths of the latter to the snow lines of mountains.

The particular Rhizopods which form the subject of the book now under consideration, are those found in fresh water only, and Dr. Leidy expressly states that his attention, during the four years engaged, was directed more to the discovery and determination of the various forms occurring in the United States, than to the elaboration of details of structure, habits, modes of development, and other matters pertaining to their history.

Although it is professedly an illustrated catalogue of the fresh water Rhizopoda of North America, we find most interesting and valuable contributions to their life history which makes us regret that time and opportunity did not permit Dr. Leidy to extend his observations in this direction, for we know how exhaustive such a treatise would have been from his hands.

Instead of writing a discursive essay upon Dr. Leidy's book, already done by many brillant writers, which, with a work so purely technical, seems the least profitable method of treating the subject,we propose to take our readers through the book, acting the part of a friendly guide, trusting by the aid of twenty-two illustrations we have reproduced for this purpose, not only to do justice to the work in question, but to convey to those who have not

In figure (3) we have a representation of the Amoeba proteus, the most simple and wonderful of Rhizopodic forms-it is, to all appearance, a structureless gelatinous mass. As the International Review states (we fear somewhat rashly) it is without organs; they are certainly not permanently visible, and so far the most intelligent research has not discovered them; but the Amoeba has the power of extemporizing such organs as are necessary for its existence, and has the means of reproducing its species. In the drawing, the In the drawing, the pseudopoda, or false feet, are seen extended, and the animal is sketched while in the act of capturing an infusorial, by the act of joining the points of two of these pseudopoda.

In the Dinamoeba mirabilis, figure (19), we find an advance made in structure, and a more specific form; the interior may be noticed to be full of desmids on which the animal feeds, and its posterior is widely expanded, so as to embrace a cord of Didymoprium.

In figure (18), Difflugia pyriformis, our Rhizopod is now found with a case or shell formed of irregular particles of quartz sand.

The empty shell of another of the same species, D. lobostoma, is shown at figure (14). The shell is composed of rectangular and oval plates, with dotted intervals.

Another of the Difflugia, D. Corona, at figure (22), still with a case formed of the same material, but of a somewhat different form, and having eleven spines; on the reverse side, the mouth would have been seen armed with teeth.

In figures (1) and (7), D. Constricta, we have further examples. In the original drawing they are colored a light redish-brown, whereas the previous examples were colored a blackish tint.

We now approach a beautiful design in form, the Nebela collaris, figure (11), the sarcode being contracted in the shape of a ball.

The design shown in figures (2) and (9), Arcella vulgaris, is still more beautiful and decidedly approaching the delicate patterns seen on the silicious valves of diatoms. The first in the original drawing is colorless, the second a light-brown, the sarcode being encysted.

In figure (20) is seen the empty shell of Cyphoderia ampulla, having a form somewhat similar to the Marine Rhizopods; the spur-like process may be noticed.

Clathrulina elegans, figure (4), is a very beautiful and remarkable form of Rhizopod, having a

two balls, and supported by a stem of the same color. In other specimens Dr. Leidy shows the sarcode balls emitting numerous rays; this appears to be omitted in the present drawing.

At figure (6), Diplophrys Archeri, is a form of a different class taken from the swamp water on the mountains of Pennsylvania. Dr. Leidy describes them as composed of multitudes of minute globular individuals aggregated in masses, which in their movement causes the whole to undergo a change of shape. The corpuscle seen in each transparent body should be colored a bright cherryred, to imitate the original drawing.

Acanthocystis chatophora, represented at figure (12), is very similar in form to the Actinophrys sol, or Sun animalcule, of the text books. The body is a finely granular protoplasm, invested with numerous delicate, silicious rays, implanted by minute basal disks; there are also numerous soft rays, like those of the Actinophrys, but distinguished from the silicious rays by the former ending in a simple pointed or furcate extremity.

We have now carried our readers briefly through Dr. Leidy's book, and have shown the beauty and variety of the forms studied. The interest attached to such investigations is obvious, and they are within the reach of every student. Considerable work has still to be done in this direction, and however great may be that done by Dr. Leidy, we feel sure that he would be the first to admit that so far the ground has been but broken.

To our mind it seems most important to concentrate future work on the genus Amoeba, for therein lies the nucleus of the most valuable discoveries, which may even be of the highest importance to the human race. What is required in this direction is the constant and continuous observation of a single individual of the species, so as to arrive at its life history. We did hope that Dr. Leidy, in his present work, would have added to our knowledge on this point; but he frankly admits that neither himself nor others profess much knowledge relating to the reproduction of the Amœba.

It is, however, a question with us, if Dr. Leidy has not missed such an opportunity during his recent investigations.

At page 49 of this work on Rhizopods we notice Dr. Leidy describes what he calls an act of cannibalism, when he saw an individual (Amoeba proteus) swallow and digest one of another species (Amaba verrucosa). We would ask, was this really an ingestive or a sexual act? Dr. Leidy takes the former view. With great respect for his

experience, we suggest that it may have been the latter, and we do so on the following ground.

FIG. 1.

undertook, with Dr. J. Drysdale, to make a continuous microscopical investigation into the life history of a certain species of Monas. For this purpose they constructed apparatus which prevented the evaporation of the water, and the conditions were made perfect, to keep the specimen in a living state for a considerable time under the microscope. They then commenced to watch the monads in turns continuously, keeping the object in view without a break in observations for many days. During this close study of these monads, Messrs. Dallinger and Drysdale also observed an act so similar to that noticed by Dr. Leidy, that we will produce both statements for comparison.

FIG. 2.

Messrs. Dallinger and Drysdale found the modes of re-production with the monads to be equally as varied as that known to exist with the Amoeba, but there was one method which particularly attracted their attention.

Two monads at times met and touched their anterior ends, swimming freely together (figure 1), their bodies then melted into each other, (figure 2); it then became a single oblong mass, the line of juncture slowly disappearing, when after from six to 24 hours, it became rounded, (figure 3); at length the edges gave way, and myriads of minute points poured out, which were watched until they developed into perfect monads.

of two Amabæ; he first speaks of their mutual approach, followed by an "embrace," when the jointed ends of the pseudopods fused together, and one sank deep into the body of the other, and eventually assumed the appearance of a sphere; further internal breaking up was then noticed, but later observation was not made. This is to be regretted as it seems quite probable that as "the melting into each other" was proved in the case of the monads to be a sexual act, that the fusion, when noticed by Dr. Leidy in the Amoeba, may have been of the same character.

The necessity for the continuous mode of study

FIG. 3.

of such forms becomes more apparent every day, especially in the case of the Amoeba, for in the very next paragraph to that just quoted, Dr. Leidy states "in my studies of Amoeba proteus I have not been so fortunate as to trace its history from an early period, nor to discover its modes of reproduction."

There are other points to which we would refer, but having already exceeded our limit of space, we can only conclude by extending our thanks to Dr. Leidy for this his latest and most valuable contribution to SCIENCE, and to those who had the foresight and judgment to direct its publication.

*Figures (5, 8, 10, 13, 15, 16, 17, 21) illustrate the series of changes observed in the swallowing and digestion of an Amaba verrucosa by an A. proteus. From Bristol Marsh, Pennsylvania, August 27, 1876, 500 diameters. Fig. (16). Amaba verrucosa, comparatively quiescent with central contractile vesicle. Figs. (5, 8, 10, 13, 15, 17, 21). Successive changes in shape and relative position of A. proteus during the act of swallowing and digesting the former. Fig. (21). A. proteus approaching the A. verrucosa with anterior short diverging pseudopods. Fig. (8). The A. proteus embracing closely the A. verrucosa by a pair of digitate pseudopods, the points of contact of which being marked by the left hand arrow. Fig. (13). The A. verrucosa swallowed and forming a large

sphere within the A. proteus. Fig. (10). The A. verrucosa, within the

latter, has assumed an oval form, and is contained within a vacuole. The central contractile vesicle, which until now had remained persistent, had become less distinct. Fig. (15). The A. verrucosa has assumed a pyriform shape within a large elliptical vacuole and its contractile vesicle disappeared. Fig. (5). The A. proteus in the act of discharging a diatom while the A. verrucosa has become doubled on itself. Fig. (17). The remains of the A. verrucosa seen as five granular balls within the A. proteus. Later these balls disappeared and their material appeared to be diffused among the granular contents of the A. proteus.

THE FOURTH STATE OF MATTER.

A REFUTATION.

Translated for "SCIENCE" by Gustave Glaser, Phil. D.

It may interest the readers of "SCIENCE" to know the opinion held in Germany respecting those phenomena

which led Mr. W. Crookes to believe he had discovered a fourth state of matter. For this purpose we have translated and abridged an article by Dr. J. Puluj, the wellknown scientist of Vienna, published in the "Chemiker Zeitung:"

According to Mr. Puluj, the beautiful experiments of W. Hittorf published in 1869, under the title "Electrical Conductibility of Gases," have received too little attention from our scientists, it may be, on account of the modest title. The scientific labors of Goldstein, and some interesting researches of Reitinger and Urbanitzky have met with the same fate. W. Crookes, the renowned English chemist, to whom the writings of the above-named gentlemen were evidently unknown, made similar experiments, the results of which did not differ essentially from those of Mr. Hittorf. His conclusions were, however, entirely new; he declared that his experiments proved a fourth state of matter.

The conception was daring, still more daring the hopes which he and his friends based upon the discovery of "radiant matter." The cause of these high expectations is the following: When an electrical inductive current is led through a molten glass tube in which the air is attenuated to of its density, there appears on the negative pole a blue (glimmering) light, which is separated by a dark space from the cluster of light at the positive pole. If a greater attenuation takes place, the cluster of light disappears and the glimmering light floats over the whole tube, while at the same time, next the electrode a second dark space appears which becomes greater with the greater attenuation. If the attenuation still further increases, the dark space fills the whole tube and the glass walls shine in a brilliant, green, phosphorescent light. Mr. Crookes now believes that this phenomenon of phosphorescence comes from the remaining gas, which at this high state of attenuation has passed into an ultra-gaseous state, a "fourth state of matter.'

But these phenomena are very different at a higher pressure. Direct measurements have shown that the phosphorescence does not appear at the millionth attenuation, and that the thirty thousandth attenuation is sufficient to produce it. Besides, this attenuated gas retains its characteristic properties, which could not be the case if by this attenuation it became dissolved into the original molecules which form, as Mr. Crookes says, the basis of all.

That the physical properties of this remaining matter are not changed, but remain in strict accordance with the kinetic theory of gases, also proves that we have no new state, but simply a gaseous state of matter. For example, the above-mentioned phenomena, in experimenting with the lighter gases, are visible at a lower altenuation than in experimenting with the heavier gases. The supposition of the renowned chemist, Dumas, that our elements are only chemical combinations of higher order, and complicated aggregates of primitive molecules, has, undoubtedly, much probability about it, but even the strongest electrical currents, and the highest temperatures, have not been able to produce this final dissolution of the elements, therefore it is not likely that a high atten

uation can.

Dr. Puluj's experiments go to show that Mr. Crookes' so-called radiant matter "consists of negative electric particles," which are torn off from the negative electrode and hurled away with immense rapidity. These elect

rode particles form a very beautiful metallic mirror on the glass walls. [Aluminum particles are the only ones which form no metallic deposits. This may be accounted for by their chemical constitution.] The conduction of the current, therefore, is effected by the convection of the electrode particles, in which static electricity is accumulated. We have here a case of molecular electric convection, analogous to that observed by Mr. Rowland in his experiments. This gentleman has demonstrated that when a movable horizontally placed metal ring, charged with static, positive or negative, electricity is made to rotate around a vertical axis, it will divert a magnetic needle suspended above it, in the same manner, as if an electric positive or negative current were to move in the same direction with, or in an opposite direction from, the rotation. These experiments of Rowland lead to the inference that an infinitely small electrical globe, in our case an electrode particle, will have a similar influence upcn a magnet. As long as the globe and magnet are at rest, it is to be expected that no alternate effect will appear, but that this will be produced as soon as the little globe is put into violent motion. Because the electrode particles are negative electric, they represent a positive e ectric current, which moves in an opposite direction from the former. The electrode particles in motion are, therefore, real elements of an electric current, and are subjected to the law of Laplace. Their deviation takes place according to the following simple law: If we imagine that a plane is placed through the direction of the motion of the electrode-particle and through the north pole of the magnet, and suppose that a man is lying upon this electrode particle in the direction of the motion, and looking towards the north pole, then the electrode-particle will be diverted towards the left hand of this man, vertical to the imagined plane. This simple law gives a sufficient explanation for all the phenomena which a magnet produces in the radiant electrode-matter, and which were observed by Mr. Crookes as well as by Mr. Reitinger and Urbanitzky. It proves that the glimmering light at the negative pole is not a "magnetic " light, but the consequence of a molecular electrical convection, and it justifies the supposition that an electrified current or vapor which is led through a tube will deviate the magnetic needle in the same manner as an electrical current going through a telegraph wire.

The law of the indestructibility of force has already solved many problems which puzzled the scientist of earlier centuries. According to the same law, we must assume that when infinitely small projectiles of radiant electrode matter are burled against the glass walls of the tube their motion is changed into molecular motion, and the glass walls are heated by the collisions, sometimes even to the melting point; but at a lower temperature the rays which are not very much concentrated only produce a phosphorescent light of the glass.

The extremely fine matter called ether, which fills all space and pierces all bodies, surrounds the molecules, as the atmosphere surrounds our globe. Each body and each molecule has in its normal state a certain quantity of this ether. When this quantity is greater than the normal quantity, the molecules, according to the “unitarian view" of elasticity, are positive electric; when it is smaller, they are negative electric.

Supposing now that a collision takes place between the negative electrode particles and the molecules of the glass walls of the tube, then the equilibrium will be restored at each point of collision and the molecules of the glass will lose their surplus of ether. At the same time a motion of the waves of ether will be observed, and this motion is felt by our optical nerves as phosphorescent light. Therefore the phosphorescence observed by W. Crookes is the result of the restoration of the ether-equilibrium and not of the heating of the glass, whose temperature during the appearance of this phenomenon is comparatively low.