504 TRANSACTIONS OF THE CANADIAN INSTITUTE. VoL. VI. 
7. In cells of Saccharomyces Ludwigit, from a culture in sap, one finds, 
rarely, structures which strikingly remind one at times of a nuclear 
organ. These structures are apparently formed of a chromatin-like 
substance, and their existence is due to a property which chromatin 
possesses of forming vacuoles in itself. When the vacuoles are fully 
formed, the portions of chromatin-like substance separating the vacuoles 
may be so delicate as to suggest the occurrence of a network like that 
of a nucleus. 
Since the foregoing paper was written, the results of an investigation 
by Ascoli," conducted in Kossel’s laboratory on plasmic acid, a variety 
of nucleic acid, have been published. The preparation of plasmic acid 
examined was obtained from yeast cells, and was found to contain 
about I per cent. of iron in a “masked” or organic form. This con- 
firms what I have hitherto advanced, and what | have described in this 
paper, regarding the presence of “masked ” iron in combination with a 
nucleic or chromatin compound in yeast cells. 
1 ‘‘ Ueber die Plaminsdure.” Zeit. fiir Physiol. Chemie, Vol. XXVIII, p. 426, 1899. 
