Estudios sobre las gónadas de la gallina 157 



Morgan's hypothesis on the secretion by the interstitial cells of a hor- 

 mone which suppresses cock-feathering is discussed. The objections 

 which might be raised against this view are the following: I. Histologi- 

 cally, at least, it is not possible to demónstrate the existence of a secre- 

 tion on the part of the cells; their much vacuolated cytoplasm may be 

 the result of fatty infiltration, parts of the medullari cords thus seconda- 

 rily becoming an adipose tissue whose special features are dependent on 

 the parenchymatous character of the cell. 2. The early appearance 01 

 the interstitial cells in the embryo and their full differentiation in the 

 newly hatched chick at a time in which the plumage of the hen is not yet 

 developed. 3. The appearance, not reported yet, in the testis of Sebright 

 embryos of interstitial cells during degeneration of the seminiferous tu- 

 bules, thus sopporting the idea that their origin is due to fatty infiltration. 



It is suggested that the interstitial cells are the remnants of the medu- 

 llary cords infiltrated with fat at an early stage of development. The de- 

 creased vitality of the cells in the degenerating cords may render them 

 unable to dispose of (/'. e. burn) the fat delivered to the gonad by the 

 blood. This fat persists as an adipose tissue proper of the ovary and is 

 perhaps connected in some way with the growth of the ova. 



