Zygospores of Sporodinia grandis. 467 
coalescence of the contents of its vacuoles. This globule at a later period 
becomes granular, the granules staining like nucleoli. A. Candida possesses 
the most highly developed coe no cent rum, which, from its earliest formation, 
is thickly beset with coarse granules that in size and staining reaction 
agree with the nucleoli of this species.’ He describes a form of oil 
which is found in globules. ‘ This results finally in a condition where 
the entire central region is occupied by a curious irregular structure which 
stains much as the oils have earlier, but which is certainly not of fluid 
consistency.’ 
It would seem highly probable from these comparisons that there is 
a close similarity between these structures of Albugo and the large oil 
plastids found in the mature zygospores of Sporodinia grandis. 
The fate of the nuclei through these varying changes is important and 
significant. Considerable difficulty, however, was encountered in matters 
of technique. Owing to the thick brittle walls of the zygospores, it was 
necessary to cut the material at 1 5-30 /jl, so that the nuclei did not stand 
out as clearly as in the preparations of younger material. It was found that 
the nuclei persist in much the same form as earlier (PI. XXXVI, Fig. 11 a). 
In the oldest stages obtained, the nuclei show a somewhat greater affinity 
for the safranin, and in many cases the whole karyoplasm stains red. 
They retain, however, their granular appearance. They are scattered 
through the cytoplasm, lying around and between the plastids as in the 
earlier stages. At the time of the appearance of the single large plastid, 
the nuclei are found in close proximity to the surface of the plastid. The 
protoplasm is found as a comparatively thin parietal layer in such stages, 
surrounding the plastid. 
In the earliest stages in the fusion of the sexual branches, and also in 
portions of the mycelium, certain red-staining crystals are evident. These 
are undoubtedly the mucorine crystals described by many working with 
the Mucors. These crystals may be either reserve or waste substances. 
In the mature zygospore, there appears an irregularly knotted or densely 
granular substance of intensely red-staining material, aggregated for the 
most part on one side of the zygospore. It reacts to the stain much as 
the mucorine crystals just described, but also strongly suggests the dis- 
organized nuclei. Until germination of the zygospores has been carefully 
worked out, however, the exact nature and function of this material will 
remain a question. These structures of the zygospore have been observed 
in material varying from eight weeks to three months after the zygospores 
had been formed in the cultures. Therefore it would seem that no further 
changes take place until germination. 
From Lager’s observations, it would seem that the zygospore, in 
germination, uses up the oil reserve, that the oil plastid is dissolved, and 
that the nuclei undergo division, forming the nuclei of the next vegetative 
