102 JOSE F. NONIDEZ 



clusters of cells. Their presence in the ovary is still an open 

 question, which the writer did not study owing to the lack of 

 suitable material. 



In young birds the wandering cells seem to be more abundant, 

 but this is probably due to the amount of tissue lying between 

 the seminal tubules. When the latter increase in size with the 

 appearance of spermatogenesis the intertubular connective tis- 

 sue is reduced to thin tracts and the wandering cells are widely 

 scattered throughout the organ to be found only in places where 

 the connective tissue is most developed. 



The similarity of the cells just described with the elements 

 reported in mammals and birds under the name of Leydig cells 

 and interstitial cells is obvious. The increase in numbers in these 

 so-called interstitial cells during the breeding season has been 

 claimed by some observers in certain mammals. In birds, how- 

 ever, the most recent studies (Pezard, '18; Stieve, '19) show 

 that there is not such an increase. On the contrary, Pezard's 

 researches in the pheasant point to a marked diminution of the 

 interstitial cells during the stage of sexual activity; they increase 

 in numbers during the winter season, when the testis appears in 

 a quiescent condition. Stieve claims that the amount of inter- 

 stitial cells in Colaeus monedula is the same whether the bird is 

 killed during the winter or during the breeding season. 



The absence of wandering cells in birds with fully developed 

 sexual characters and the considerable variation in their numbers 

 in different cocks make it very hard to believe that such cells 

 are concerned with the secretion of a specific hormone influencing 

 the secondary sexual characters. The origin of such cells in 

 adult cocks further shows that in all probability they are wan- 

 dering cells similar to those described in the general connective 

 tissue.^ They arise from small lymphocytes migrated from the 



* The connective tissue of the fowl has been described by Solucha (quoted by 

 Danchakoff, '16 c). Since the paper is written in Russian, I have not been able 

 to read his description of the wandering cells. The transformation of the small 

 lymphocytes into histiotopic wandering cells has been mentioned by Danchakoff 

 in several of her papers. The polymorphism of the cells found in the gonads sug- 

 gests that they may belong to the same kind of elements, although they are proba- 

 bly slightly modified on account of environmental conditions which are not found 

 elsewhere in the connective tissue. 



