GLANDULAR CELLS OF THE FROG'S PANCREAS 375 



into the cytoplasm in the form of filaments, which are nothing 

 other than mitochondrial filaments or chondriocontes. These 

 steps of changes must be a visible manifestation of the nuclear 

 and cell activity; these changes are not yet completed with the 

 formation of the mitochondria, but the latter must undergo fur- 

 ther changes in order to perform the special function of the 

 cell. I will return to this question further on. 



C. Fat-like granules 



R. Heidenhain ('75, '80) was the first to point out the presence 

 of fat granules in the pancreas cell. He allowed dilute alkalis to 

 act upon the pancreas cell, and found that the zymogen granules 

 grew pale, while certain granules, which he took to be of fatty 

 nature, are characterized by the resistance which they offer to 

 that reagent. The fatty granules have since been recognized by 

 several investigators in various glands; in the pancreas by 

 Mathews ('99) and Laguesse ('00), more recently by Bensley 

 ('11), Arnold ('12), Mislawsky ('13), and Maximow ('16). 



1. Technique. In preparations fixed in pure osmic acid or 

 in mixtures containing osmic acid, such as Meves', Benda's, etc., 

 the granules in question take on only a pale grayish color; in 

 the Mislawsky's fixative and in osmium-sublimate with formalin 

 prefixation they appear as black granules; they are also impreg- 

 nated with the Faure-Fremit's and Golgi's method. In fixatives 

 containing a large amount of acetic acid, they appear as clear 

 vacuoles which remain unstained in either of the stains employed ; 

 in preparations fixed in Meves', Benda's, Altmann's, Champy's, 

 etc., fluid and stained with iron-haematoxylin, they take on a 

 brown to black color. 



It will be seen from the above account that the granules in 

 question are not blackened with osmic acid alone, but stain a 

 grayish color which grows more and more pale in the subsequent 

 manipulation of the piece and sections. In order that they may 

 be blackened by osmic acid, the action of a reducing agent is 

 necessary. In the cases above mentioned, formalin and pyrogal- 

 lic acid serve as such. In the Mislawsy's mixture formalin to- 

 gether with osmic acid act upon the piece. Formalin may also 



