MR. A. J. EWART ON ASSIMILATORY INHIBITION. 373 
the oven at the particular temperature required. They are then 
moistened, part at once examined, and the rest kept in the damp 
chamber, and portions examined from time to time. Since when 
a closed cell preparation with Bacteria is made, the Bacteria do 
not exhaust the enclosed dissolved oxygen and come to rest for 
a few minutes, it follows that however rapidly and carefully the 
preparations are made, sure and certain results are only given a 
quarter of an hour after the plants have been moistened and the 
preparations made. If examined before this, the Bacteria may 
be moving, not because any evolution of oxygen has taken place, 
but because the oxygen originally present has not yet been 
exhausted. 
The plants in Table C were previously tested to make certain 
that they could withstand desiccation. After being dried in air 
at 20° C., and kept in a desiccator for a day or two, they were 
found all to remain living, and to show at once on moistening 
an active power of assimilation. Unicellular plants form very 
good working material, as they are hardly at all affected by 
manipulation, and each cell can be examined separately. The 
only precautions necessary are to avoid pressure and excess of 
either Algal material or Bacteria. 
The results obtained are, as regards the inhibition of assimi- 
lation, similar to those obtained with Mosses, but the experiments 
are of especial interest as enabling a comparison to be made 
between Algal cells when free, and when combined with Fungi 
to form Lichens. 
Table D gives the main results of the experiments with 
Lichens and with a vascular eryptogam, Selaginella lepidophylia. 
The resistance which the latter plant offers to drying is well 
known; and Bert and Bureau * mention that it is able to with- 
stand heating to 60° C., the duration of the exposure not being 
given. 
A glance at the table shows that Selaginella lepidophylla is 
markedly affected by a day’s heating at 55° C., and is killed after 
a day (24 hours) at 60°C. For the experiments living branches, 
the leaves of which showed an active power of assimilation, were 
eut off, allowed to roll up and become air-dried, and then heated 
to the required temperature. The first leaves to be affected by 
* Bert and Bureau, “ Note sur la reviviscence du Selaginella lepidophylla et 
du Ceterach officinarum,” in Oomptes-rendus de la Société de Biologie, 1863. 
