608 Price —Some Studies on the Structure of the Ptant Celt 
that possibly only the larger ones are then seen. In any case, they are 
much more clearly seen by dark-ground methods. The ‘ plugs 5 of proto- 
plasm in the older parts of the hyphae have the appearance of being made 
up of close aggregations of these vesicular bodies, so that these older plugs 
may be really accumulations of waste or excreted material. The finer 
plasma particles with their rapid motion are quite indistinguishable in direct 
illumination. 
The study of this fungus gave the idea that particles of graded size 
from the smallest to the large vesicles existed in the colloid complex here, 
and it also suggested the possibility of a spontaneous reversibility between 
the sol and the gel states of the protoplasm. This idea was followed further, 
and is discussed again below. 
No sign of any structures which could be identified as nuclei was 
made out. 
Pythium . 
The hyphae of the species used (P. Debaryanum ), although much 
smaller, showed much the same phenomena as those of Saprolegnia. 
Protoplasmic plugs are frequently present, and it was found that at the 
basal end, below these, there was a general thinning out, and that in this 
region protoplasmic movement frequently occurred. Sometimes this oscil- 
lation of particles was present throughout the length of the hypha. Particles 
seemed to be graded in size much as in Saprolegnia. 
Mucor. 
Cultures were made by dropping the spores into sterilized liquid media, 
so that the hyphae were obtained free from air bubbles (Andrews, T2). 
The hyphae again exhibited characters of the same nature as those just 
described, but interesting results were obtained by a study of spore 
germination. 
Movement of very fine particles occurred, and ‘ plugs ’ composed of 
larger motionless particles were also present, with much the appearance 
of coagulated protoplasm. These were thus judged to be in the hydrogel 
state. On fixation with glacial acetic acid added to the edge of the cover- 
glass, little change took place in these plugs, but after the complete fixation 
of the whole of the protoplasm, the plugs were no longer to be distinguished 
from the rest of the contents of the hypha. This seems to indicate that 
the plugs are certainly to be regarded as protoplasmic, but that they 
represent a different state of aggregation, or a different condition of the 
protoplasm. Further evidence was derived from germination of the spores 
(PI. XLI, Fig. i). 
It should be mentioned that the so-called plugs are not to be regarded 
