884 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
taken place, for the vegetative mycelia of ordinary fungi are 
readily killed by drying. 
Certain of the conclusions which Jumelle draws from his 
experiments on the effects of dry heat on assimilation cannot be 
passed over without criticism. He concludes that (s) heating 
alters chlorophyll whether the cell contains water or not, but that: 
the protoplasm remains uninjured for a much longer period, and. 
here the presence or absence of water is an important factor ; 
(5) the stoppage of assimilation is a permanent one and is due 
to a destruction of the chlorophyll, the protoplasm remaining. 
living and capable of respiration; (c) it is owing to this ready 
decomposition and destruction of the chlorophyll that lower 
green plants, although often capable of drying, offer little more 
resistance to dry heat than higher plants do ; (d) chlorophyll is 
destroyed by heat before protoplasm is; (e) non-chlorophyllous- 
plants are those which offer the greatest resistance to heat, and. 
hence he concludes that the Alga in a Lichen is killed long before 
the Fungus is, which does not appear to be the case. 
The stoppage of assimilation produced by dry heat is not 
necessarily a permanent one and is never accompanied by any 
visible alteration in the colour, form, shape, or condition of the 
chlorophyll bodies so long as the cell remains living, though of 
course it is always possible that an invisible alteration may occur.. 
The presence or absence of water is of just as much importance 
in the preservation of the vitality of the chlorophyll grain as in 
that of the protoplasm. The presence or absence of chloropbyll 
has little or nothing to do with the resistant power of plants 
to dry heat.  Non-chlorophyllous plants are not necessarily 
more resistant to dry heat than chlorophyllaceous plants. It is 
doubtful whether any plants, chlorophyllous or non-chlorophyllous 
are, in the vegetative condition, more resistant to heat tban. 
the mosses in the experiments given in Table A. Chloro- 
phyll is certainly not destroyed by heat before protoplasm is.. 
In certain cases, it is true, a cell may remain living for a few 
hours or even days without the power of assimilation returning, 
but microscopical examination fails to detect any change in the 
assimilatory apparatus until the death of the cell takes places. 
It is very possible that both the duration and degree of the 
desiccation to which the plants are submitted are of importance in 
inducing the inhibitory after-effect upon assimilation. The pre- 
ceding tables show the importance of the first factor, and that of 
