IRON COMPOUNDS IN ANIMAL AND VEGETABLE CELLS. 245 
in his investigations the species 8S. cerevisie, 8. Ludwigii, 
and S. Pastorianus, states that he found in the two former a 
nucleus provided with a membrane and a nucleolus, the latter 
spherical and homogeneous and of a diameter one third that of 
the nucleus. The remaining portion of each cell is occupied 
by a cytoplasmic network with fine meshes, whose nodal points 
readily absorb colouring matters, and, in the opinion of 
Janssens, constitute the granules of Raum. He claims to 
. have observed mitotic stages of the nucleus, which obtain when 
budding commences and when spore formation occurs. 
Two observers only, Briicke! and Krasser,? have denied the 
existence of a nucleus in the yeast-cell. Krasser in his later 
publication asserts that the body described by Mdller as a 
nucleus is not such an organ, and he found, after employing 
Moller’s methods on beer yeast-cells, that the latter possessed 
no body like the one described by that observer. He further 
observed that the bodies described by Moller as nuclei, after 
being submitted to digestion with artificial gastric juice, gave 
no evidence of the presence of nuclein. The occurrence of the 
latter substance in yeast-cells, which is readily demonstrable 
in a macro-chemical way, Krasser attempted to show micro- 
chemically, and, after many failures, succeeded in finding it in 
a few specimens in the form of granules at the side of the body 
regarded by Moller as a nucleus. 
I have followed the methods of hardening and staining 
adopted by Moller, for the purpose of ascertaining the nature 
of the body considered by him to be a nucleus, and have 
compared the results thus obtained with those found in yeast- 
cells after hardening the latter in saturated solutions of cor- 
rosive sublimate and staining them with hematoxylin and 
eosin. I have also used Flemming’s fluid for hardening, and 
stained preparations so made with safranin. Moller’s methods 
certainly do reveal, now and then, a structure like that which 
1 “Die Hlementarorganismen,” ‘Sitzungsber. der K. Akad. d. Wiss. zu 
Wien, Math.-Nat. Classe,’ 1861, vol. xliv, Abth. 2. 
2 “Ueber das angebliche Vorkommen eines Zellkerns in den Hefezellen,” 
‘Oesterreich. Bot. Zeits.,’ 1885, No. 11; also “ Ueber den Zellkern der 
Hefe,” ibid., 18938, p. 14. 
