BIRMINGHAM NATURAL HISTORY AND MICRO. SOCIETY. 21 
plants, and which will ultimately prove of the very greatest import- 
ance. By these discoveries, in which several botanists, notably 
Mr. W. Gardiner, B.A., of the Jodrell Laboratory at Kew, have 
taken part, a number of the old ideas about the cell structure of 
plants are completely overthrown. Of late years gradual advances 
have been made in the direction which will be more particularly 
specified further on, and several eminent men have prophesied on 
a@ priori grounds that the discovery which is now made would come 
to pass. But still the honour of actually proving the fact belongs 
alike to Professor Hillhouse and Mr. Gardiner, who arrived simul- 
taneously and independently at similar results, thus adding another 
instance, to those in which science already abounds, of two minds 
working at distant places in the same direction, and at the same 
time. 
Professor Hillhouse’s lecture was of a preliminary character, and 
was devoted to clearing the ground for the full comprehension of 
the importance and meaning of his results. All physiologists teach 
now that animal and vegetable organisms alike consist of minute 
sacs or bags of some substances, within which is contained frag- 
ments of that part of the organism in which its life essentially 
resides, to which they give the name of “ protoplasm ;” the enclos- 
ing membrane with its contents forms what is known as a “cell.” 
Between the cells of animal and vegetable organisms, however, they 
point out a number of differences, of which we need only mention 
one. That is, that while animal cells are separated from one 
another only by a layer of protoplasm, slightly different in its 
character from the protoplasm which it encloses (and known as 
*‘cement-substance”), the cells of a vegetable organism, on the 
contrary, are surrounded by a layer of a substance totally unlike 
protoplasm, known by the name of “cellulose ;” and it was always 
taught that the protoplasm of the cell was completely shut off 
by the cellulose membrane from all communication with the pro- 
toplasm of the neighbouring cells. In fact, each vegetable cell was 
considered as an isolated individual. It is this last doctrine that 
Professor Hillhouse’s observations have finally disproved. In 
several which he has examined, of a sufficiently diverse character, 
taken in connection with Mr. Gardiner, to afford a satisfactory 
basis for induction, he has shown that the protoplasmic contents of 
neighhouring cells are connected by delicate threads of protoplasm, 
which pierce the cell wall by minute pores, and are continuous from 
cell to cell. They constitute, in fact, a sort of nervous system, but 
in all probability are confined to those kinds of cells in which the 
cell wall is not extensively thickened. 
The existence of such a connection could be prophesied on the 
following @ priori grounds:—In the first place, there are found in 
many plants what are called “‘sieve-tubes,” the walls of which are 
