688 Proceedings of Royal Society of Edinburgh. [sess. 
remains in an invisible state, unless the phosphorus and iron it con- 
tains are unmasked and revealed by dyes as directed by MacCallum. 
When the cell begins to take up material from the blood (serum 
albumin, etc.) this prozymogen quickly links on some albumin 
to become zymogen in the form of granules, nucleo-albuminous in 
nature, which is probably a still less stable compound than the 
prozymogen ; it now reacts as a feeble base to eosine, and hence is 
stained red with that dye. It is also readily soluble when brought 
into contact with a weak acid, either in the cytoplasm or elsewhere. 
In other words, both chromatin and zymogen have the same 
nuclein radicle, their difference in staining property and solubility 
depending on the amount of albumin linked on to it. 
Formation of Zymin. 
I 
Prozymogen. 
Chromatin. 
I 
Proteid of 
lymph. 
Albumin of 
Nucleolus. 
I 
i 
(Effete.) 
With regard to the question of repair of the nucleus, it can only 
be brought about by the passage into it of substances from the 
