1894.] Chemico-Physiological Discoveries: The Cell. 111 
that it is the nucleic acid of the nucleus which is the primary 
cause of the pronounced color shown by this portion of the 
cell on treatment with aniline dyes. 
With this understanding of the wide-spread distribution of 
nucleins throughout all animal and vegetable cells, let us con- 
sider somewhat more in detail the character of their decom- 
position or cleavage products, for this may give us a clearer 
insight into their general nature. As already stated, the 
nucleins thus far studied yield on treatment with dilute 
mineral acids a row of peculiar crystalline nitrogenous prod- 
ucts, the xanthin bases so-called, the true antecedent of which 
Kossel has shown to be nucleic acid. Hence, the yield of 
these bodies, which, by the way, belong to the uric acid group, 
must depend upon the amount of nucleic acid contained in 
the given nuclein. The wide-spread distribution of these 
bodies, throughout the animal organism especially, wherever 
cell activity is pronounced, their close connection with uric 
acid and their evident origin in the nucleic acid of cell nuclei 
are facts of great physiological importance, since they throw 
possible light upon the physiological function of the cell nu- 
cleus and at the same time point to a genetic connection 
between the nuclein bases and uric acid. This phase of the 
matter, however, we cannot now consider, but there are one or 
two points connected with these nuclein bases that we cannot 
afford to pass by. First, the bases themselves are four in 
number, viz.: adenin, guanin, xanthin and hypoxanthin, all 
well defined bodies of known chemical constitution. Among 
these, adenin stands foremost. It is, to be sure, the one most 
recently discovered, but its characteristic chemical nature and 
constitution give it a peculiar prominence the others do not 
possess. It is not only a product of the chemical decomposition 
of pure nuclein by dilute acids, but it is widely distributed in 
nature, and its distribution in the organs and tissues of 
animals and plants corresponds to its genetic relationship to 
the characteristic constituent of the cell nucleus. Thus Kos- 
sel has obtained it from the pancreatic gland and from the 
spleen, also from yeast cells and from tea leaves, but found it 
18 Zeitschrift fiir physiologische Chemie. Band 12, p. 241. 
