Albert C. Eycleshymer 305 



Miiiot, 92, 474, iiiids the " *ame peculiarity in tiie cluck, but later the 

 nuclei lose this main granule and have instead a number of smaller ones." 



The changes in the quantity and quality of the chromatin during the 

 growth of the muscle cell is more striking than the changes observed 

 in the other nuclear structures. In the early stages (6-7 mm.) the 

 karyosomes are comparatively small, and quite evenly scattered through 

 the nucleus; soon, however (10 mm.), the chromatin shows a tendency 

 to aggregate in large karyosomes, which are irregularly disposed. These 

 large masses of chromatin then (17-26 mm.) become grouped in the 

 axial and peripheral portions of the nucleus, the peripheral layer being 

 much thicker on the side of the nucleus, which is applied to the fibril- 

 lated surface of the myoblast. 



This series of changes resulting in the greatly increased quantity of 

 chromatin goes on hand in hand with the increased cytoplasmic activity 

 manifested by fibrillation. Another striking change in the nucleus dur- 

 ing the phases of greatest cytoplasmic activity is the entire absence of 

 plasmosomes. We find in these changes a most remarkable and perfect 

 correspondence to the changes known to occur in the nuclei of gland 

 cells during phases of activity. I quote the following from Stohr, 00, 

 " The nuclei of many gland cells also exhibit varying appearances cor- 

 responding to the changing functional state; in empty cells the nucleus 

 exhibits a delicate chromatic network and a conspicuous nucleolus, while 

 in the loaded cells the nucleolus is invisible and the chromatin-cords 

 appear in the form of coarse fragments." Garnier, 00, likewise holds 

 that the most constant correlation between the structure of the nucleus 

 and cytoplasm during glandular activity is the augmentation of chro- 

 matin. 



The peculiar condensation of chromatin, being more accentuated on 

 the side of the nucleus which is applied to the fibrillated surface, suggests 

 that a condition is thus brought about which is more favorable for the 

 correlation of nuclear and cytoplasmic activities. While I know of no 

 observations which are of precisely the same nature, there are many 

 which show that there is a marked increase in the contact surfaces of 

 cytoplasm and nucleus during periods of great cytoplasmic activity. 



Korschelt, 89, has pointed out a number of instances in the eggs of 

 insects where similar changes have been observed. The most striking 

 of these is found in the secreting nurse-cells attached to the eggs of 

 Forficula. Korschelt states that the peripheral position of the nucleus 

 and its richness in chromatin are undoubtedly correlated with cell- 

 metabolism. Carlier, 99, states that in the gland cells of the newt's stom- 



