198 INTERNAL SECRETIONS 



function of the interstitial cells of mammals, based especially 

 on the experimental observations which are above recorded. 



A new point has lately been made by Goodale. As the 

 interstitial cells containing granules are eosinophile cells, 

 Goodale (1919) is disposed to consider them as leucocytes. 

 He remarks that similar cells are to be found also in other 

 organs, such as the thymus of the moulting drake, where they 

 are abundant, and in the thyroid, pineal and pituitary glands, 

 where they have been found, though they are not common. 

 The question has been taken up by Nonidez (1920). He studied 

 the gonads of embryos and young chicks by differential staining 

 methods ; he concluded from his observations that the granule- 

 laden interstitial cells are derived from primitive blood cells 

 or haemocytoblasts, or in other words from mesenchyme cells. 

 The granule-laden interstitial cells are connected with typical 

 eosinophile granulocytes (or leucocytes) by a graded series of 

 stages. Besides these interstitial cells primitive undifferentiated 

 mesenchyme cells and small lymphocytes are also present in 

 the intertubular space of the testicle of the adult bird. These 

 may become transformed, according to Nonidez, in the adult 

 bird into several types of cells, also into cells closely resembling 

 the interstitial cells in the testicle of mammals; these cells 

 have a finely granular acidophile cytoplasm; they are vacuo- 

 lated and contain fat; the nucleus is round. They are not, 

 however, a constant element in the testes of the adult bird, 

 and may be absent. Nonidez considers them to be wandering 

 cells. As to the function of all these different types of cells 

 Nonidez thinks that neither the granular cells, nor the inter- 

 stitial cells derived from the small lymphocytes, can have a 

 specific endocrine function. The granulocytes and the modified 

 small lymphocytes are not restricted to the gonads occurring 

 elsewhere in the general mesenchyme; Nonidez says that the 

 small lymphocytes may perhaps have some bearing on the 

 development of the sex characters in the young bird, but their 

 inconstancy in the testis of the adult bird shows that they are 

 not necessary for the maintenance of these characters. It 

 seems hkely to Nonidez that the fat stored in the interstitial 

 cells derived from the small lymphocytes may be used by the 

 cells within the seminal tubules, or even transformed into a 

 specific hormone which exerts its influence on the sex characters. 

 It may be remembered that Bouin and Ancel (1905 c) consider 



