500 Wager . — The Nucleus of the Yeast-Plant . 
finds rounded delicate cells with a thin but clear cell-wall, 
containing clear contents with more or less delicate granules 
which singly or in groups occur on the inner surface of the 
cell-wall, and (almost?) always a large, round flat body (a 
cytoblast). 
Briicke (’61) objected to Nageli’s observations, and says 
that, without wishing to maintain that Nageli had not true 
nuclei before him, he is able, with improved apparatus and by 
observations on living material as well as on material treated 
with iodine and acetic acid, to state that no nucleus is 
visible, and remarks that nobody is justified in taking bodies 
of varying size and number, such as often occur, for nuclei. 
Schmitz (’79), in his valuable paper on the nuclei of the 
Thallophytes, was able to show however, by the use of 
haematoxylin, that the Yeast-cell possesses a body which 
stains more deeply than the rest of the protoplasm. It occurs 
about the middle of the cell in the protoplasm near the 
vacuole, and he regards it as a nucleus. 
Strasburger also (’84, ’87) was able, by means of the same 
staining fluid, to demonstrate the nucleus described by Schmitz. 
He says that on fixing with picric acid and staining with 
haematoxylin, a rounded nucleus is to be seen near the centre, 
stained more deeply than the remainder of the cell-contents. 
In the living unstained condition a nucleus is not visible. 
Zalewski (’85) found that the presence of a nucleus can 
be very easily rendered evident by placing the Yeast-cells 
in pure water for some time and staining with haematoxylin. 
The nucleus is oval in shape and possesses a small nucleolus 
in the centre. It stains more deeply than the other part 
of the protoplasm, which forms a dense layer round the 
nucleus. In budding cells the nucleus could not be dis- 
covered, nor in cells in which spore-formation was taking 
place ; in these cases it was probably undergoing division, 
as a nucleus was observed in the fully formed spores and 
budded cells. 
Objections to these observations were brought forward 
by Krasser (’85), who was able to observe granular structures 
