THE GONADS OF THE FOWL 101 



interstitial cells of mammals and have been regarded as such in 

 the testis of the matm-e cock (Mazzetti, '11; Reeves, 'IS)."* Fig- 

 ures 27 and 28 represent two of these cells drawn from sections 

 of the testis in a mature hen-feathered Campine cock. The 

 cytoplasm is acidophile, finely granular in structure, and shows 

 irregular vacuoles. In sections stained for fat droplets of the 

 latter substance can be sometimes detected in the cytoplasm. 

 The nucleus is round and shows a coarse chromatin network in 

 which one or two nucleoli are embedded. The position of the 

 nucleus within the cell-body is variable, but quite often it is 

 excentric. The irregular outline of the cell coupled with the usual 

 excentric position of the nucleus indicates that in all probability 

 such elements may wander through the connective tissue. The 

 polymorphism of the cell-body is very marked in extreme cases, 

 and the cell may possess short branches or blunt pseudopods; 

 otherwise they tend to be polygonal or round in outline. This 

 condition seems to be related to the presence of large vacuoles in 

 the cytoplasm. 



The cells just described are not a constant element in the 

 make-up of the testis of the mature bird. "V\Tiile those represented 

 in figures 27 and 28 were found in an adult hen-feathered Campine, 

 inspection of the testis in another hen-feathered cock of the same 

 breed, castrated when it was over four months old, failed to show 

 the occurrence of wandering cells. That such cells are also found 

 in cock-feathered birds is proved by their presence in the testis 

 of an adult Rhode Island Red cock and other cock-feathered 

 birds of the same breed. When present, the cells under consid- 

 eration appear usually scattered in the intertubular spaces, but 

 in some places they may be grouped in diffuse agglomerations. 

 When they are very abundant they may even give rise to true 



■* Besides these authors, several observers have also regarded these elements 

 as interstitial cells. Reeves has represented in his paper two kinds of cells which 

 have no genetic relationship. Those represented in his figure 1, drawn from a 

 cock eighteen months old, correspond to the wandering cells derived from the 

 small lymphocytes. The cells represented in his figures 2 and 3 drawn from slides 

 of a much younger bird arise as a transformation which takes place in the cells of 

 the sexual cords during a late stage in development. The origin of such cells 

 will be described in another paper. 



