GLANDULAR CELLS OF THE FROG'S PANCREAS 373 



From the staining reactions of the mitochondria, the inference 

 would appear justifiable that it is quite different from the chro- 

 matin substance of the nucleus. In alum-haematoxylin prepa- 

 rations, the chromatin takes on a violet color, whereas the 

 mitochondrial filaments remain unstained and appear as fine, 

 clear canalicules in a violet background (fig. 83). In the Meves', 

 Champy's, etc., preparations, on the contrary, the nucleolar 

 corpuscles and the mitochondia are deeply stained, while the 

 chromatin corpuscles are easily decolorized. This difference in 

 staining reactions is inconsistent with the hypothesis of Gold- 

 schmidt and his pupils that the mitochondria are identical wth 

 the chromidia which, according to them, are nothing other than 

 the chromatin substance passed out of the nucleus. Since, on 

 the other hand, there can be no doubt that the mitochondria are 

 derived from the nucleus, I do not also agree with Benda, Meves, 

 and their supporters in regarding them as mere plasmic struc- 

 tures. Just as little plausible are the views held by some that 

 they are either products of differentiation of the plasm or bodies 

 drawn in from the outside. 



That the nucleus is the centre of propagation and metabolism 

 of the cell is now fully recognized by various investigators; this 

 is evidenced by the experiment that the cell-body devoid of its 

 own nucleus cannot further continue to exhibit its vital activity. 

 While the chromatin is generally regarded, from its behavior in 

 mitosis, as forming the material basis of heredity, its relation to 

 the metabolic activity of the cell has been a question which re- 

 mains at present unanswered. Concerning the biological sig- 

 nificance of the nucleolar substance, there is also wide diver- 

 gence of opinion among different investigators. In the following 

 I will first consider two opposed views advanced with regard to 

 the relation between the nucleolus and the metabolism of the 

 cell, and then summarize my opinion. 



According to the view of some histologists (Flemming, '82; 

 Rhumbler, '93; Montgomery, '99), the nucleolus must be con- 

 sidered as stored-up nutritive material for the chromatin sub- 

 stance or for the whole nucleus. Haecker ('93, '95) and his sup- 

 porters claim, on the contrary, that the nucleolus is not nutri- 



