52 
D. D. CUNNINGHAM. 
at the same time affirming that it thus becomes evident that 
all living powers are cognate, and that all living forms are funda- 
mentally of one character.^^^ It cannot be supposed that any 
difference of opinion should exist on this point, and, such being 
the case, it must be evident to all that the effects produced on 
vegetable protoplasm by insufficient nutrition are of a nature 
analogous to those occurring under similar conditions in the pro- 
toplasm of animal tissues, and that the study of the former may 
afford much information in regard to the latter. Taking this 
into consideration, the reason that a series of experiments should 
have first been carried out on the influence of starvation on vege- 
table protoplasm becomes manifest. 
In selecting particular vegetable organisms as the subject of 
experiment, the primary desiderata appeared to be — 1st, to 
employ such as were capable of easy and accurate observation 
under the various conditions to which they were to be subjected ; 
and, 2nd, to employ such as were familiar to the observer, so as 
to secure the best opportunities of fairly estimating the actual 
influence of various alterations in these conditions. Two species 
of mucorine fungi were accordingly selected. Both of these had 
been special objects of study for some years, and both are readily 
susceptible of artificial culture under conditions extremely 
favorable to accurate observation. An additional recommenda- 
tion of these organisms as subjects of experiment lay in the fact 
that, due to their fungal nature, the processes of nutrition in 
them s-how a more accurate correspondence to those in most 
animals than they do in vegetable tissues containing chlorophyll. 
In regard to animal tissues the great point appeared to be to 
secure such as could be submitted to observation during the life 
of the organism to which they belonged, or in any cases under 
circumstances involving the smallest possible amount of manipu- 
lative interference. In order to meet these requirements, the 
animals selected as subjects of experiment were tadpoles. Brom 
the extreme transparency of the tissues in certain parts of these 
organisms, and the ease with which large numbers of them may 
be procured and kept under observation, they afford exceptional 
facilities for the conduct of experiments ; and although it may 
not be permissible to deduce exact conclusions on all points from 
the phenomena observed in cold-blooded animals regarding those 
which will present themselves in higher forms under similar 
conditions, yet in so far as the general effects of defective supply 
of nutritive material on the living elements of the tissues are 
concerned, there is good reason to suppose that the phenomena 
in both cases must be much alike. 
> ‘ On the Physical Basis of Life,’ Lay Sermons, Addresses, and Reviews, 
by T. H. Huxley, LL.D., P.R.S., pp. 120 — 146. 
