294 J. S. FERGUSON 



D. FTHROrjJA 



The occurrence of fibrils blackening; with silver in the mesen- 

 chymal cells suggests a possible identity with th(^ fibroglia fibi'ils 

 of Mallory ('03, '04) for such fibrils were found by that observer 

 to be al)undant in developing connective tissue. In order to 

 accurately c()m])are the fibrils shown by these two special methods 

 one must first consider the mature tissues, only thereafter the 

 developing tissues. 



In matui'e tissues Mallory states that fibroglia fibrils ''are not 

 very common in normal tissues except possibly in one situation 

 and have to be hunted for with an oil immersion lens." This is 

 certainly not the case with the argentiferous fibers which occur 

 al)undantly in a great variety of places among normal tissues 

 and which are of sufficient size to be seen as networks among 



It 



Fig. 12 The basket-cells of ;i coil gland of the human finger-tip, darkened by 

 haematoxylin. Haidenhain's iron-haeniatoxylin. ("ainera lucida; occ. 1, obj. 

 i\ horn. im. 



the other fibers with very low h:iagnification. Again the 

 staining reactions of the two sets of fibrils are different. Mal- 

 lory describes the basement membranes as the " one situation" 

 where fibroglia fibrils are common in normal tissues, and the sub- 

 epithelial l)asket-cells of the sweat glands — regarded by Benda 

 ('93, '94) as muscle cells — as the place where the largest fibroglia 

 fibers occui'. As these last fibers can be easily located they form 

 a definite unit for comparison. With Mallory's stain they are 

 red; with iron haematoxylin they l)lacken when the stain is not 

 too much extr-acted (fig. 12). Both of these reactions are char- 

 acteristic; for fibroglia, and, as AIcGill ('08) has shown, they are 

 also characteristic for myoglia fibrils. But with silver impregna- 

 tion these fibers are not in the least blackened, nor is the thin 



