So that germinal matter may multiply very fast, and produce less formed material than in the normal state, or germinal matter, which in the normal condition produces very little formed material may be placed under circumstances in which a considerable quantity of formed material is produced. It is therefore very essential to study the conditions which effect these very striking modifications in the germinal matter of different structures.

No. 24 shows the relation existing between the germinal matter and formed material of the tendon of a kitten, and in No. 25 the germinal matter and the formed material of the true skin from a fœtus, at the 7th month, are seen.

The first is a structure, in which the changes are exceedingly slow; the second is one in which we know changes are occurring constantly, and with comparative rapidity throughout life. You will admit, I think, that in all probability the germinal matter, in the one preparation, corresponds to that in the other, -fibrous tissue being the result of the growth of the germinal matter of the tendon,-nerves, capillaries, fibrous, elastic, and adipose tissues being formed from the particles of the germinal matter in the last specimen. The relation of the germinal matter to the formed material, in quick and slow growing tissues, is well seen in the foetus, from the 6th to the 9th month.

No. 26 shows the bulbs of two or three hairs from the foot of a kitten. The bulb is much wider than the shaft of the hair. The elementary parts, in this region, are composed almost entirely of germinal matter. Higher up the formed material increases, and each elementary part undergoes condensation. Much of the water of the elementary parts is absorbed, and the whole, consequently, contracts and becomes firmer. The manner in which the formed material is produced is seen very beautifully by examining the elementary parts at different heights in a specimen of hair prepared with carmine. According to the language generally employed, the nucleus gradually diminishes while the cell increases in extent, as we ascend from

the deep part of the bulb, upwards towards the shaft, until, when we arrive at the dry part of the hair, the cells (cortex) are destitute of nuclei. The nature of the change is explained very simply by the view which I am advocating, and follows of necessity, because the supply of nutrient material to the elementary parts gradually diminishes from below upwards.

No. 27 is a thin section from a tumor which grew very rapidly. It appeared at the lower angle of the scapula of a boy, aged 12 years, and when first noticed was about the size of a bantam's egg. In six months it measured twenty-seven inches in circumference. It was firm and hard, and was intimately adherent to the scapula. The case occurred in the practice of my friend, Dr. Elin, of Hertford, to whom I am indebted for the specimen. The friends would not consent to have the mass removed, and it continued to grow for about twelve months after its first appearance, when hæmorrhage occurred from some large veins on the surface of the tumor, and the boy died of exhaustion. The mass was of the same character throughout. Dr. Elin says: "It surrounded the scapula which was partly absorbed. The bone was very brittle, breaking like a piece of glass. I have no doubt that the tumor originally spread from the periosteum of the margin of the scapula." An aunt or cousin of the boy seems to have died of a similar tumor several years ago. The relation of the germinal matter to the formed material is well seen in this specimen, and the free but irregular mode of growth of the elementary parts is also well shown.

No. 28 is a section of tumor, about the size of a walnut, connected with the parotid gland. The remains of some of the gland-follicles are seen, and as the elementary parts in them are dead, and are undergoing disintegration, they are not coloured by the carmine. On the other hand, the actively growing tissue contains a large amount of germinal matter, every separate mass of which is darkly coloured. The growing tissue insinuates itself in every direction, and where the parts

of the growth first formed are becoming old and are losing their vital activity, offsets from the more recently developed parts, may be seen invading them.

No. 29 is an interesting specimen of the so-called cancercells, which were passed in the urine of a patient suffering cancer of the uterus.

In these morbid growths we have no difficulty in demonstrating the existence of germinal matter and formed material, and even cursory observation of the tissue affords abundant evidence of its wonderful power of rapid growth. Although it would not be possible to distinguish a single elementary part of one of these growths from an elementary part removed from certain healthy tissues, the striking irregularity of the structure, the absence of that orderly arrangement exhibited by all healthy textures, and the great extent of tissue exhibiting precisely the same characters, afford conclusive evidence as to the nature of the structures under consideration.

If the elementary parts of a tissue multiply to an unusual extent, and thus overstep the limits assigned to them in the normal state, a growth is produced which may only differ from the healthy tissue with respect to its bulk, with reference to the position which it may occupy or to which it may spread, and in the relation it bears to other textures. Adipose tissue, fibrous tissue, cartilaginous and bony tissues often form tumors of considerable size in direct continuity with the normal structure. It would seem that just at the point where these outgrowths originate, the restrictions under which growth occurs normally, are to some extent removed, and here we see the power of unlimited growth, which is a property of the germinal matter of all tissues, manifesting itself.

In the normal state there is reason to believe that, of the nutrient material distributed to the tissues, a certain proportion is absorbed by the germinal matter, and at length undergoes conversion into tissue, while any excess is probably taken up by lymph corpuscles, and, perhaps, by the white blood corpuscles,

which increase in number, and is at length restored to the blood. It is probable that, in many of the textures in the interior of the body, a balance of nutrition is thus maintained in the healthy state. If, however, the active powers of the germinal matter of the tissue be impaired, in consequence of some inherent deficiency, or through the influence of a pabulum not fitted for its nutrition, or by some change in the formed material which separates the germinal matter from the nutrient fluid, the tissue must suffer; and, as new material is not added to it as fast as the old is removed, it must waste. In this case a large proportion of the nutrient matter will be taken up by lymph corpuscles, which will rapidly increase in number, and the pabulum, which ought to have been made into tissue, will be again restored to the blood.

It seems not unreasonable to assume that a result, corresponding to that which is effected in the skin by the removal of the superficial layers of the cuticle and hair, and by the escape of the secretion of the sebaceous and sudoriparous glands,—in mucous membranes, by the falling off of the superficial layers of epithelium,—and in glandular organs by the conversion of formed material into the secretion, is brought about in tissues distant from such surfaces as the muscles, nerves, and some other textures, through the influence of little masses of active germinal matter known as the lymph and white blood corpuscles, and thus the débris is again restored to the blood, to be resolved into matters which may serve as pabulum, and compounds which must be eliminated. I must not, however, pursue this part of the question further, just now, and will only offer the suggestion that in certain cases, where an unusual growth of the tissue takes place at a particular point, it is just possible that here the arrangement, through the influence of which the tissue is maintained within its proper limits in the normal state, and prevented from extending indefinitely, is absent.

LECTURE V.

Of Morbid Growths.-Of the Development, Growth, Nutrition, Decay, and Removal of Tissues.-Of Secretion. Of the Changes occurring in Living Matter.

MR. PRESIDENT AND GENTLEMEN,

WHEN we were considering the changes occurring in elementary parts during their growth, we saw that the proportion of the germinal matter to the formed material altered as the elementary parts increased in size. At first each consists of a mass of germinal matter, which is separated from its neighbours by a very thin layer of soft formed material. At this period of its life it may divide and subdivide, and several separate masses may be produced. Gradually, however, as each elementary part recedes from the vascular surface, the germinal matter ceases to divide and subdivide, although it still absorbs nutrient material and grows. Inanimate matter becomes germinal matter, and germinal matter becomes formed material. At last, when the elementary parts are separated by a considerable stratum of younger ones from the nutrient surface, the formed material becomes harder and drier, and less permeable to moisture. The changes taking place in the germinal matter, now imprisoned in a firm thick layer of formed material, occur