612 Price. — Some Studies on the Structure of the Plant Cell 
particles with a rapid Brownian movement, and a very considerable free 
path of motion. It may be mentioned here that the protoplasm escaping 
from a broken hypha showed particles of two orders of mean magnitude — 
the larger particles, which seem to build up the hydrogel plugs of the 
hyphae, and extremely minute ones, which in contrast appear as fine as 
dust, but which are very like those remaining in the old spore-case just 
described. Both types, however, seem to produce liquid sols with the 
mounting medium. 
The formation of the e plugs ’ occurs as the hyphae increase in length — 
the ‘ active protoplasm * occupies less and less of the total volume. They are 
composed (PL XLI, Fig. i) of aggregations of motionless particles, forming 
more or less opaque band-shaped plugs to the hyphae. Several of these 
occur in the length of the hypha, and, especially in the older ones, con- 
siderable lengths may be thus occupied. In some cases a motionless 
aggregation of this nature occurs right at the end of an apparently growing 
hypha, so that it appears as though this state must represent an active 
condition of the protoplasm for growth. The action of a fixative such as 
glacial acetic acid has already been described, the contents of the fixed 
hypha failing to show any such differentiation. 
Streaming movements (Andrews, T2) were also seen to take place 
in the hyphae. The smaller particles were carried along in a rapid stream, 
as though by an invisible flowing fluid. The larger particles may also be 
carried, and seem to collect to a certain extent at the plugs. Larger vesicles 
(of oil or glycogen ?) also occur, but are generally not numerous. 
The aecidiospores of Melampsora Rostrupii , Wagner ( Caeoma mercuri- 
alis ), T riphragmium Ulmariaeh and Phragmidium disciflorum i ]a.mes ) when 
fresh and mounted in water, all show much the same appearance under 
dark-ground illumination. The spore-wall is generally slightly marked 
or papillose on the outside, and thus rather interferes with the critical 
observation of the contents. The latter have a striking appearance of intense 
activity due to Brownian movement, so that the internal condition of the 
spore is quite different from that of the Mucor spore just described. The 
appearance as of a boiling mass is due to a number of yellow particles, or 
rather little globules, as these can be seen to escape on crushing the spore 
and so liberating its contents. On germination of the spores, these globules 
pass into the germ tube, and the phenomena here observed are somewhat as 
already described for fungal hyphae. 
The globules may represent some reserve substance of the nature of 
glycogen, or oil suspended in the protoplasm. The latter, since it allows 
of the free movement of these, must be in the fluid or hydrosol state, but 
must apparently contain extremely minute particles as the disperse phase. 
It seems more logical, perhaps, and more in accordance with the facts, 
1 Aecidiospores or primary uredospores of T. Ulmariae. 
