Cytology of P yttrium tdtimum , n. sp. 297 
direct divisions or fusions. Another explanation might be 
found in the supposition that the appearances were caused 
by two nuclei coming into contact with one another. We 
have to note, however, that the nuclear membrane is dis- 
tinctly traceable as a definite line, sometimes dipping inwards 
so as to cause partial constriction, but never separating the 
two chromatic masses from one another. Further, the number 
of nuclei remains fairly constant when these abnormal nuclei 
are present. There is neither a diminution nor increase in 
their number, and indeed they appear in the reproductive 
organs only when these are at rest. At present it is therefore 
impossible to do more than regard them as nuclei with 
anomalous structure. The future may be able to throw light 
on their genesis and fate. 
Figs. 41 to 45 illustrate sections of germinating oospores 
designed to show the fate of the reserve globule. Incidentally 
they show the changes in the wall and the nuclei at the same 
time. It is clear that the reserve globule becomes more 
spongy, breaks up into separate masses and gradually under- 
goes digestion, absorption, and assimilation. The last traces 
of this reserve material may be seen in the form of deeply 
stained granules in Figs. 44 and 45. 
We have still to consider the structure of the mycelium 
and conidia as traceable in sections, and the phenomena 
associated with the germination of the latter. Fig. 46 is that 
of a section of a young conidium obtained from a four-day 
culture, Fig. 47 that of a conidium fixed when about one 
month old. The first was fixed in Hermann’s solution, the 
second by immersion in Flemming’s stronger solution for one 
hour. Observation of the living material had led me to 
expect differences in the number of the nuclei. There were, 
however, no differences of importance observable. The differ- 
ence in the number of nuclei observed in the sections comes 
well within the limit of variation. One could in fact obtain 
scores of sections in one slide with the numbers in the opposite 
proportion. The older conidia are generally vacuolated, and 
the unequal distribution of the vacuoles leads to an unequal 
