Connective Tissue, Nerve, and Muscle. 521 



this paper and my acquaintance with the literature of the subject. It 

 is, however, well known that while twenty years ago the so-called con- 

 nective-tissue corpuscles were believed to be concerned in the formation 

 of elastic tissue, with the development of Virchow's doctrine of cel- 

 lular pathology, this opinion seems to have been gradually abandoned, 

 even by those who, like Virchow himself, had originally maintained it. 

 Eanvier, whose investigations seem to have been conducted in singular 

 independence of contemporary theories, holds that the first step in the 

 appearance of elastic tissue is the formation of "granulations refringentes" 

 traceable in the fully developed fibres. 



In the spring of 1873, while investigating the structure of the touch- 

 c.orpuscles of the finger, I found that the much-discussed cellular ele- 

 ments of these bodies, which colour in gold and carmine, anastomose with 

 each other by means of fibres that resist prolonged maceration in con- 

 centrated acetic and dilute mineral acids, and I described them, in the 

 account I gave of the results of my investigation, as " elastic tissue fibres." 

 At the same time I found that similar cells and fibres form a thick net- 

 work in the corium. Simultaneously, Spina made his exhaustive study 

 of the connexion of the elastic fibres in tendon with the walls of the 

 cell, to which I have already referred. 



Since that time, I have continued to subject the skin and subcutaneous 

 tissue to treatment by different methods, and the results have been con- 

 firmative of those I obtained in Vienna. Shortly expressed, the con- 

 clusion I have come to is, that, in skin, all the branched cells form elastic 

 tissue on their surface and on their processes, and that there is no elastic 

 tissue anywhere that is not so formed. 



The cells found in connective tissue are divisible, as I believe, into two 

 distinct classes. There are, first, the flat cells which never branch, and 

 which, when treated by nitrate of silver, present appearances identical 

 with those produced when the flat cells of serous membranes are simi- 

 larly treated ; secondly, there "is the system of branched cells in its va- 

 rious forms. As contrasted with each other, they may be described simply 

 as the flat and branched cells of connective tissue*. Between these . 

 two classes of cells there is no transition and no anatomical continuity. 

 The forms of the branched cells embrace all the gradations between the 

 fine network of a lymphatic gland and the anastomosing network of the 

 strong fibres in skin and tendon. They are distinguished by their pro- 

 cesses, their capacity to form a substance that resists acetic acid the 

 power, namely, of forming the resisting element specially characteristic 

 of elastic tissue. That they do not all exercise this latter power to 

 the same degree, does not constitute a sufficient difference to make 

 it necessary to regard them as separable into classes essentially distinct. 



The ligamentum nuchae may be taken as the type of the stronger forms 



* To flat cells the term placoids has been applied by Dr. Burdon Sanderson, the 

 equivalent of the 



