388 LOUIS MAX HICKERNELL. 



consideration of some of the functions of chromatin in general. 

 R. Lillie ('02) and others have shown "that in many tissues the 

 nucleus is the chief agency in the intracellular activation of 

 oxygen; and further that the active or atomic oxygen is in 

 general most abundantly freed at the surface of contact between 

 nucleus and cytoplasm." Now the parts of the nucleus which 

 take part in these oxidations must be the chromatin and, perhaps, 

 the nuclear membrane. It seems reasonable to suppose that 

 the lack of the normal amount of water in the nucleus causes 

 the chromatin to be unable to interact with the nuclear membrane 

 in bringing about oxidations, and the nucleus adapts itself to 

 the new conditions by rearranging its chromatic content in the 

 manner described. 



I have implied in the preceding paragraph that the chromatic 

 material goes no further than the nuclear membrane and that 

 there it is deposited to make the typical ring structure. While 

 this may be and probably is true in cases of relatively incom- 

 plete desiccation, I think there is much evidence that in many 

 cases the chromatin either does pass through the nuclear mem- 

 brane or it is so changed chemically within the membrane that 

 its presence cannot be detected by ordinary methods. A com- 

 parison of different nuclei in the figures of sections of dried 

 animals shows that the peripheral chromatic ring is not nearly 

 uniform in thickness in the different nuclei. I interpret this as 

 meaning that varying amounts of chromatic material have 

 been able to pass to the cytoplasm, the ability or inability to 

 do so depending perhaps for one thing upon the permeability of 

 the nuclear membrane. 



It will be remembered in this connection that immediately 

 upon the addition of water to the dried animals the chromatic 

 ring thickens and regains its normal staining power. This 

 fact also is, I think, capable of two. interpretations. It may 

 indicate that chromatic material which moved in some form 

 into the cytoplasm during the dry period immediately begins to 

 return to its normal position when moisture is restored or it 

 may be that the drying process caused the chromatin to lose its 

 staining power to such an extent that its volume only seemed 

 to be diminished. From the appearance of the sections I do 



