mode of condensation between ketonic compounds and aldehydes. The methylene-groups in malonic and acetoacetic ethers are directly combined with two CO-groups, and hence the combination takes place with the greatest ease. With pyruvic acid and diethylacetether, the condensation takes place with much greater difficulty, as the only points capable of condensing are directly united to but one CO-group. In the case of acetoacetic ether I found the condensation to be complete in 18 hours, whilst with the diethyl ether only about 25 per cent. had condensed after a lapse of four days.

A solution of cinnamyl diethylacetic ether in chloroform at once decolorises bromine, and on spontaneous evaporation of the chloroform, leaves behind an oil which finally solidifies. It was recrystallised from ligroïn, and gave on analysis the following figures :—

0.1343 gram substance gave 0.2318 gram CO2, and 0·0604 gram H2O.

0.1306 gram substance gave 0.1120 gram AgBr.

This dibromide crystallises in small colourless prisms, which melt at 54-55°, and are distinguished from the original ether by their easy solubility in alcohol and petroleum.

I have also attempted to effect the following condensations of di-substituted acetoacetic ethers, dichloroacetoacetic ether with benzoic and acetic aldehydes, and benzylideneacetoacetic ether with the same aldehydes. I have tried all the methods of condensation with which I was acquainted in these cases, but in no case was I able to isolate any condensation-product, and in fact with the dichlorinated ether I was unable to find any trace whatsoever of a reaction. The dichlorether is therefore an exception to the rule that all substances which have a CH3-group directly combined with a CO-group are capable of forming compounds with benzoic aldehyde, with elimination of one molecule of water.

BEHAVIOUR OF MONO-SUBSTITUTED ACETOACETIC ETHERS WITH BENZOIC

ALDEHYDE.

Condensation of Monoethylacetoacetic Ether and Benzoic Aldehyde. This condensation was effected similarly to that with the diethyl ether. The product, however, did not boil so constantly as in the

former case, and as it showed no tendency to solidify, it was not so easy to purify. After the first distillation it contained 2-3 per cent. of chlorine, and on every subsequent distillation it was slightly decomposed, and on analysis always showed an excess of carbon. It was, however, obtained in an approximately pure condition, and gave on analysis the following numbers :

I. 0.246 gram substance gave 0·6694 gram CO2, and 0·1678 gram H2O.

II. 0.1878 gram substance gave 0.5092 gram CO2, and 0.1249 gram

The substance in the purest state I obtained it, is a yellow pleasantsmelling oil, boiling at about 210° under a pressure of 22 mm.

It is evident that if this condensation is analogous to that of the diethyl ether, the compound must still contain one hydrogen-atom possessing the property of being replaced by sodium in the same way as aceto-acetic ether; and further, that if this atom of hydrogen be replaced by a C2H,-group, the identical cinnamyldiethylacetic ether will be obtained. I therefore acted upon the cinnamylmonoethylacetic ether, first with sodic ethylate, and afterwards with ethyl iodide, and obtained a substance which on recrystallisation from ether, melted at 101-102°, and gave on analysis the following numbers:-C 74:53 per cent., H 8.31 per cent., whereas theory requires C 74-45 per cent., and H 8.03 per cent. The substance was identical in all its properties with, and in fact was cinnamyldiethylacetic ether. I may here remark that Crismer (loc. cit.) has found that monoethylmalonic ether is quite incapable of condensing with benzoic aldehyde.

In conclusion I wish to point out-1st. That acetoacetic ether is capable of condensing with aldehydes of all descriptions, and that the condensation takes place only in the methylene-group, but with the greatest ease. 2nd. That mono- and di-substituted acetoacetic ethers (with the exception of the dichlorether) are capable of condensing with benzoic aldehyde, but that the condensation is very much more difficult to effect, and takes place only in the methyl-group.

208

XXXI.-Contribution to the Chemistry of "Fairy Rings."

By Sir J. B. LAWES, Bart., LL.D., F.R.S., J. H. GILBERT, Ph.D., F.R.S., and R. WARINGTON.

THE circles of dark-green grass which frequently occur on pasture land, and have long been known by the name of "Fairy Rings," have naturally attracted the attention of botanists and vegetable physiologists, and various explanations of their occurrence have been given. It has long been supposed that the luxuriant growth of grass constituting the ring is connected with the growth and decay of fungi, which so serve as manure for the grasses which succeed them. Among the numerous explanations of the fact that the growth assumes the form of an extending ring, perhaps the one which for some time received the greatest attention, was that based on the theory of Decandolle, according to which the excretions of a plant are prejudicial to the growth of plants of the same description. It was supposed that the excretions of fungi were detrimental to their recurrence on the same spot, and hence they developed only externally to the ring of their previous growth.

The first explanation of the luxuriant growth of, the rings, put forward from a more purely chemical point of view, was that of Professor Way, in a paper "On the Fairy Rings of Pasture, as illustrating the use of Inorganic Manures," which was read in the Chemical Section of the British Association at Southampton in 1846, and was published in the Journal of the Royal Agricultural Society of England, 7, 549. He analysed the ash of some of the fungi, and also of the grass of a fairy ring. From the results of these analyses he explains the growth of the fairy rings as follows:-" A fungus is developed on a single spot of ground, sheds its seed, and dies. On the spot where it grew it leaves a valuable manuring of phosphoric acid and alkalis, some magnesia, and a little sulphate of lime. Another fungus might undoubtedly grow on the same spot again; but upon the death of the first the ground becomes occupied by a vigorous crop of grass, rising like a phoenix, on the ashes of its predecessor." The growth of the grass as an extending ring, and not as a disc, he further explains by the fact of the removal of the grass, and with it "the greater part of the inorganic materials which the fungus had collected." He adds, that the nitrogen of the fungus must not be left out of consideration, but that he believes-"it is to the inorganic elements that the effect is chiefly to be ascribed."

Buckman, on the other hand, whilst admitting that fungi are fre

quently found on or just outside the ring, considers their occurrence by no means essential to the formation of the ring, and that it may be produced by any cause unfavourable to the growth of a circular disc of grass. At the same time he says-" there is reason to think that rings to which the fungi have not become attached soon break up" (Veterinarian, May and June, 1870).

Almost from the commencement of the Rothamsted experiments, the circumstances of the development of fairy rings have been observed with much interest, as affording a striking example of what may be called "natural rotation." It was thought that if the source of the nitrogen of the fungi growing in fairy rings were determined, some light might perhaps be thrown on the source of the nitrogen of the Leguminosa, which are grown separately, in rotation with the cereals and other crops, or in association with the grasses in the mixed herbage of grass land. In a Rothamsted paper in 1851 (Jour. Roy. Ag. Soc., 12, 32), the subject was referred to as follows:"A beautiful illustration of the dependence for luxuriant growth of one plant upon another of different habits, such as we have shown above, may be found in the case of the 'fairy rings,' where the fungus, by virtue of its extraordinary power of rapidly accumulating nitrogen from the atmosphere during its growth, taking up the minerals which the grasses, from their more limited power in this respect could not appropriate, provides an abundance of the nitrogenous manure so effective in the growth of the grasses which are observed to spring up with great luxuriance wherever the fungus has grown or fallen."

Here, then, it was assumed that it was the nitrogen, rather than the ash-constituents of the fungus, to which the manuring action was mainly to be attributed. Even at that time the characteristic effects of mineral and nitrogenous manures respectively, on the growth of gramineous crops, were sufficiently established by field experiments to leave no doubt that the dark colour and the luxuriant growth of the grasses on the rings were intimately connected with a liberal supply of nitrogen as manure. But it will be observed that the source of the nitrogen of the fungi was then supposed to be the atmosphere.

Since that time much directly experimental and other evidence has been acquired as to the sources of the nitrogen of green-leaved plants; and, although absolute proof is still wanting on some points-and it might well be that plants of such opposite characters as fungi might have a different source-yet doubt as to the atmospheric source of their nitrogen gradually increased. Accordingly, in 1874, an attempt was made to obtain direct experimental data on the subject. Samples of soil were taken of a fixed area and to a fixed depth within, on, and outside a fairy ring; and in each the nitrogen was determined.

The results showed the lowest percentage of nitrogen in the surface soil within the ring, a higher percentage under the ring, and a higher still outside it. The obvious conclusion was, that the soil within the ring had lost nitrogen by the growth of the fungi, and the subsequent luxuriant growth and removal of the grasses. But so important a conclusion required confirmation. Accordingly, in a short paper by one of us entitled "Note on the Occurrence of Fairy Rings," published in 1875 (Jour. Linn. Soc. Bot., 15, 17), the general indication only was stated, reserving the publication of the numerical results until they should be confirmed. The soils of other fairy rings have since been collected and investigated, and it was intended to extend the inquiry further; but, owing to the unfavourable weather of the last few years, the rings which had been under examination have disappeared. Under these circumstances, and as the general bearing of the results already obtained is unmistakable, it has been decided to put on record both the earlier and the later results, without waiting for further repetition or extension.

Before entering upon a consideration of the experimental results in question, it will be well to refer a little more in detail to some of the circumstances of the occurrence of a fairy ring.

It is probable that the fungi growing on grass land owe their occurrence, in the first instance, to the accidental droppings of animals (or birds); and it seems to depend on the conditions of soil, season, and association, whether the growth is limited to the original spot, or whether it extends, and an annually increasing ring is formed. If the soil be rich, or highly manured, or the season very favourable for luxuriance of the general herbage, the probability is that the fungi will not be reproduced, and a patch only will be developed. It is under opposite conditions, that is, where the soil is poor, that the development of rings is generally observed.

The growth of fungi being once established from some extraneous cause, such as above referred to, they will on decay supply a rich nitrogenous and mineral manuring to the adjacent herbage. A patch of dark-green luxuriant grass succeeds. This being cut or eaten off, the soil becomes the more exhausted the more luxuriant has been the growth. Accordingly the vegetation within the ring is generally less luxuriant than that outside it. In the case of mere patches, some examinations of the soil in spring and autumn have not shown a marked development of mycelium. But on digging into the turf immediately outside a ring, it is generally found penetrated by a white cobweb-like mycelium, extending to a depth of several inches, and sometimes even to a foot or more. When the mycelium is abundant, the soil is remarkably dry, and can with difficulty be wetted, as if it were greasy. The mycelium is most abundant in the soil