PREFACE.

ALTHOUGH the observations recorded in the following pages have necessarily led the author to give expression to a general view or doctrine which seems to him to account for the appearances observed, he thinks it right to state that the conclusions which have now assumed a definite form have gradually grown upon him during the course of observations extending over a period of several years. In fact some of the drawings in this volume, and others which have been published elsewhere, equally favorable to the view, were made long before any specific theory had been arrived at.

An attempt has been made to account for the anatomical characters of certain tissues and to trace the changes which take place during the development, growth, nutrition, and decay of individual textures. The results obtained, it need scarcely be said, are very

incomplete, but they are quite sufficient to encourage the author to pursue more extended observations in this direction. There is every reason to believe that as our knowledge of the minute alterations occurring in the elementary parts of tissues increases, the views now generally held upon the nature of the healthy and morbid changes occurring in the organisms of the higher animals and man will become much clearer and more simple than they now are.

The author believes that the numerous facts he has brought forward and the drawings which he has published will be considered sufficient to justify him in opposing the views generally entertained on the structure of the connective tissues. Although the conclusions arrived at are very different from those generally entertained in Germany, it must be borne in mind that observers in that country are by no means agreed upon the elementary facts upon which the connective tissue theory may be said to rest. For instance, Kölliker's explanation of the appearances observed in tendon, and his description of the formation of the so-called cells and intercellular substance in this structure, in cartilage and in bone, by no means accords with those of many other authorities.

The author has not attempted to give all the opinions entertained on this and other matters, or to show in what points he agrees with or differs from previous observers, for had this plan been followed out the present volume would have been twice its size and would probably have found very few readers. Indeed the author fears that the detail into which he was forced

to enter on the subject of the connective tissues will be devoid of interest to many of those who nevertheless are exceedingly fond of anatomical investigation. He is however quite ready to discuss the matter more in detail in German periodicals if his fellow-workers in Germany desire it.

The author has devoted much time during the last twelve years to the preparation and demonstration of tissues. Although he feels quite certain that the processes he has adopted will be very much improved, he cannot but believe that the preparation and preservation of specimens of the tissues of vertebrate animals, in which both capillaries and nerve fibres are very distinctly demonstrated, many of the latter being less than the 1-50,000th of an inch in diameter, with the germinal matter (cells and nuclei) of all the different tissues stained with carmine, is a step in advance. Moreover, many of the points delineated in the drawings can be clearly demonstrated in the portable microscopes even to large classes, and it is certain that specimens which require the highest magnifying powers (700 to 1,700 diameters) will also be capable of class demonstration when the mechanical adjustments of the portable microscopes have been made more delicate.

The tissues, of which illustrations are given, have been hardened so that very thin sections were readily obtained, without resorting to the processes of boiling or drying. Some of these preparations even give one the idea that more would be demonstrable if a higher magnifying power could be brought to bear on them. The highest power which the author has yet been able

to obtain is the 1-26th of an inch, made by Messrs. Powell and Lealand, magnifying 1,700 diameters.

The preparations described in the descriptive list of specimens and most of those figured in the plates are in the author's possession, and he will be happy to show them to any one who desires to examine them.

Some anatomists have sought occasion to disparage those who, as they think, waste so much time in mechanical operations and manual work, while other eminent men have assailed as worse than useless the process of injection and other methods of preparation. It seems to the author that all future advance in minute anatomy must depend upon improvements in the methods of examination. The fact has not been generally recognised that the soft delicate tissue which forms the terminal portion, and is in reality the active part, of nerve, becomes altered immediately after death, and by the action of water many soft structures are at once destroyed. The only hope therefore of ascertaining the arrangement, and of forming a true notion of the action of the most important tissues of the body is in the discovery of plans of investigation which shall prevent the breaking down and disintegration into granular matter which immediately follows death. The only means of effecting this seems to be the rapid impregnation of the tissue with some fluid which at once arrests disintegration, and how is it possible that tissues can be so equably, quickly, and thoroughly impregnated with a preservative fluid, as by the process of injection?

The Lectures, which have in part appeared in the