appearance to disappear, while it renders the so-called nuclei and their lines of connection with each other more distinct. At the same time in fully formed tendon there is a delicate network of yellow elastic tissue, the fibres of which for the most part pass round the bundles of the white fibrous tissue, and are therefore, upon the outer part in contact with the oldest part of the tendon, or with the formed material which was first produced.

In fœtal tendon the acid does not produce so striking a change. The wavy bands, the fibrous appearance of which is not so very darkly marked as in the adult, in many cases remain; and thin bands can always be detached and are easily demonstrated to be directly continuous with the so-called nuclei. In many specimens of young tendon it is difficult to demonstrate a single fibre of undoubted yellow elastic tissue. The yellow elastic fibres are always less numerous in young than in adult tendon, while the so-called nuclear fibres are two or three times more numerous in the former than in the latter. The proportion of yellow elastic tissue, therefore, does not seem to be dependent upon the so-called nuclei. The yellow fibres where they exist are not connected with the nuclei, and are separated from them by white fibrous tissue. These elongated parallel nuclei of tendon are not concerned in the formation of yellow elastic fibres, but the germinal matter of which they are composed does become converted into the white fibrous tissue of the tendon. This germinal matter, like that of other structures, and the fibrous material which it produces, when young and imperfectly formed, are not rendered transparent by acetic acid and other reagents, while the fully formed tissue undergoes the alteration which is so well known. I should state that I have studied the action of reagents on specimens which have been treated with carmine and soaked in glycerine. This latter substance possesses the property of retarding the action of chemical reagents, and by the slow and gradual effect produced it is advantageous.

Fig. 33, Plate V., shows the appearance of a small piece of a longitudinal section of the tendon of a child at birth. The prolongations from the masses of germinal matter (cells or nuclei) are well seen, and their communications are tolerably numerous. The specimen has been pressed, and the disposition of the oval nuclei has therefore been altered. The processes are distinct enough in some places, but most of them gradually become lost among the wavy fibres with which all are connected and of which they are but the early stage. Although they somewhat resemble fibres of yellow elastic tissue in their general appearance and in their power of resisting the action of acetic acid, they are not of this nature; their outline is irregular, and when examined with very high powers they have a granular appearance, which is very different to the sharp outline and homogeneous appearance of the yellow elastic tissue. In the dead tissue they may be called tubes, but they are artificial tubes, and do not convey nutrient juices during the life of the tissue. The germinal matter and imperfectly formed tissue of which they consist, cannot be regarded as a nutrient material. It is merely an early stage of the fibrous tissue.

Moreover, it must, too, be borne in mind that the appearance so remarkably distinct in fig. 33, which results in part from the pressure to which this specimen has been subjected, is not constant. It is not seen in the specimen of adult tendon represented in fig. 34, where fibres of yellow elastic tissue are found, nor in that of the kitten, fig. 31, and in the fascia of the frog there is no more indication of such an arrangement than there is in cartilage. In some specimens of the tendon of the child which have been stretched and pressed, the appearance of stellate cells and communicating tubes is most distinct, but that it depends upon an alteration produced in the nuclei, and upon the displacement and tearing of some of the young tissue connected with them is sufficiently proved by the appearance being produced by pressure, by its absence in parts of the specimen not subjected to pressure, by the great variation in

the appearances when the arrangement is produced, and by its entire absence in certain specimens. The dark lines in fig. 33, continuous with the cells, are not elastic fibres at all, neither are they elastic tissue at an early period of its formation, as will be shown. Elastic tissue when it exists in tendon is not connected with these nuclei.

The altered appearances produced in the same piece of tendon by mere stretching and pressure are shown in Plate VI, fig. 34. The fact illustrated in the drawing is most important. The drawing was carefully copied from a specimen which exhibited the usual regular arrangement before pressure was applied, and may perhaps help to explain the cause of the different statements which have been made with reference to the appearance of the so-called cells or nuclei.

How are we to account for the delicate fibres of yellow elastic tissue surrounding the fibres of many specimens of tendon? Their existence is undoubted but they are not in sufficient number to be considered as essential constituents of the tissue, and they are not to be detected in all forms of white fibrous tissue. For the most part they wind round the bundles. By great patience you may occasionally succeed in finding a nucleus connected with these fibres, but when this is so the nucleus is very small, and quite distinct from those I have described as connected with the white fibrous tissue. It is, however, very seldom that I have been able to demonstrate this nucleus in connection with the yellow elastic tissue in tendon, and from the fact that I have seen this appearance result from alterations produced in an undoubted capillary vessel, I am disposed to explain the very few cases in which I have met with it in this manner.

As a rule the fibres encircling the bundles of the white. fibrous tissue are certainly not connected with nuclei. The nuclei which are constantly present, exhibit a linear arrangement at every period of the growth of tendon. The yellow elastic tissue on the other hand is not arranged in parallel lines,

but the delicate fibres of which it is composed form a lax network.

As to the tubular nature of these fibres of yellow elastic tissue. In yellow fibrous tissue, from many situations I have seen prolongations of germinal matter as in other tissues, but I have completely failed to prove that these yellow elastic fibres generally are tubular, and concerned in the distribution of nutrient matter. Over and over again, I have stained the nuclei amongst the fibres of yellow elastic tissue with carmine, while not a single fibre exhibited the slightest alteration. I cannot think, therefore, that these fibres at any period of their existence, have any such office as that of distributing nutrient fluid to the tissues in connection with which they are found.

No. 37 (fig. 30) is a portion of the white fibrous tissue from the fascia covering the muscles of a frog, and this specimen is quite destitute of the yellow elastic tissue. The oval masses of germinal matter, coloured dark red with carmine, are, however, very distinct, and their continuity with the fibrous tissue is equally positive.

Fig. 36, Plate VI, represents a vertical section of a piece of thick lymph lying between the liver and diaphragm, from a man who died of scrofulous enlargement or amyloid degeneration of the liver. The mass adhered slightly to the fibrous capsule of the liver, but it could be removed without being torn. In one or two places it adhered very intimately, and had undergone conversion into white fibrous tissue, but the layer generally was not in vascular connection with the adjacent parts. Similar extensive layers of lymph were found over the surface of the intestines. The germinal matter and formed material can be seen most distinctly in the specimen, and the arrangement of the meshes of fibrous tissue is almost as regular as that observed in the proper tissue of the cornea.

We, therefore, conclude that tendon, like fascia and other textures consists of germinal matter and formed material, and that the formed material bears the same relation to the germinal matter as in other tissues; that the so-called nuclei of the nuclear fibres are the masses of germinal matter which produce the fibrous tissue of the tendon; that the elongated fibres intervening between the cells or nuclei consist of soft material undergoing the process of conversion into the harder fibrous tissue. This soft substance is soon broken down after death and liquefied, and these straight tubes, which are artificially produced, seem to intervene between the oval masses of germinal matter, so that we have a series of straight tubes pursuing a longitudinal course in all parts of the tendon, and exhibiting here and there a dilated portion.

This is not the only tissue in which oval masses of germinal matter form, as it were, straight continuous chains parallel to each other. In dentine, in the muscular fibres of the heart, in the muscles of the frog generally, and in some of the muscular fibres of insects, a similar continuity between oval masses of germinal matter is observed. These might be regarded as tubes containing granular matter, but this would be a very artificial view of these structures, and I think it more natural to speak of them as germinal matter surrounded by the formed material which they produce. In some cases they are found on one side of the fibre, the production of the formed material having taken place entirely on one side of the masses of germinal matter. There are no tubes or cavities in the living tissue; the space is occupied with the most important part of the whole structure, the substance upon which the integrity of the whole and the reproduction of new tissue depend, and if this be destroyed during life, the destruction of the firm fibrous tissue must at length necessarily result, because the passage of fresh particles of fluid through its substance must cease, and in consequence the character of the fibrous tissue soon becomes altered.