Wager. — -The Nucleus of the Yeast-Plant. 501 
in Yeast-cells after staining, but could not recognize a nucleus, 
and was not able therefore to confirm the statements of 
previous observers. He points out that there is no specific 
staining reaction for the nucleus. The absence of a definite 
nucleus in the Yeast-cell is supported by the very rapid 
growth of the organism. The Yeast-cell possesses nuclein, 
but this is distributed through the protoplasm. 
Both Hansen (’86) and Zacharias (’87) succeeded in demon- 
strating the presence of the body described as a nucleus by 
Schmitz. 
Zimmermann (’87) states in his text-book (Morphology 
and Physiology of the Plant-cell) that he observed in 
a preparation stained with haematoxylin a deeply stained 
body which might be regarded as a nucleus, but he does 
not think this has been satisfactorily demonstrated. In a 
more recent communication, however (’93), he gives,, in an 
account of the literature of the subject, this observation 
as supporting the view that the Yeast-cell contains a nucleus ; 
and in a footnote referring to the doubt expressed by Krasser 
that Zimmermann had not been able to satisfy himself that 
a nucleus was present, he expressly states that in his figure 
given on p. 23 he regards the deeply stained body as a 
nucleus and the lighter body as a vacuole. 
The evidence in favour of the presence of a nucleus is so 
far perhaps not very convincing or satisfactory, and Raum 
(’91), after an examination of a large number of various kinds 
of Yeast, came to the conclusion that it was not possible 
to state definitely that a nucleus is present in the Yeast-cell. 
On staining, with methylene-blue and Bismarck-brown, cover- 
glass preparations which had been allowed to dry and had 
been fixed by heat or corrosive sublimate, he found that 
the protoplasm stained brown and that a number of granules 
present in it stained black ; whilst on staining with eosin 
and methylene-blue, the granules became dark violet. The 
number of granules varies in the different species and also 
their arrangement. They are not always present. Whether 
they are composed of nuclein is doubtful, but the author 
