22 THE MICROSCOPICAL NEWS. 
pierced by obvious pores, and it has been proved that threads of 
protoplasm pass through these openings. In the second place, it is 
now known that when the protoplasm of a cell is contracted by salt 
solution or other similar reagent, the ball of protoplasm which col- 
lects in the centre remains connected with the cell-wall by fine 
threads, which terminate in a knob, and, penetrating the cell-wall 
by a “pit” or depression to its “middle layer,” are attached firmly 
thereto. Now these pits in contiguous cells are often opposite, so 
that between the knobs attached to the base of each pit there inter- 
venes only the thin “middle layer”; the portion of this layer, which 
lies immediately between the bases of the opposing knobs, is seen 
to be streaked transversely in such a way as to suggest that 
minute threads of protoplasm pass from one knob to the other. 
Professor Strasburger, of Bonn, was convinced that “‘the difference 
between this case and that of the obvious apertures in the ‘sieve- 
tubes’ was only one of degree.” 
Again, it is known that an influence exerted upon one cell of a 
plant can be transmitted to the adjoining cells. For instance, if 
one leaflet of the sensitive plant be touched it approaches the 
opposite leaflet to which it is closely applied. The impulse is 
transmitted to the next pair of leaflets, from them to the next, and 
soon. It then reaches the base of the pinnule, from which it 
travels to the other pinnules of the same leaf, all of which close 
their leaflets in the same manner. The impulse then travels to 
the base of the leaf stalk, and the whole leaf drops down. Now, 
this and other movements of plants inevitably suggest the existence 
of some mode of direct communication between cell and cell, but 
it has been hitherto unknown how this communication was effected. 
It has been constantly denied that plants possess anything of the 
nature of a nervous system, but Professor Hillhouse’s observations, 
and those of Mr. Gardiner, supply the gap, and show how the 
influence is transmitted. 
Professor Hillhouse also gave a short vesumé of the growth of 
our knowledge about protoplasm, and a few other ideas necessary 
to put the hearer into a position to understand the subject into 
which he will enter more deeply ina future address. The lecture 
was illustrated by a number of very skilfully prepared microscopic 
slides, which showed the chief points on which the lecturer had 
dilated. One especially, prepared fromthe filmy fern ( Zodea ), the 
cell contents of which had been contracted twenty-four hours before 
by aten per cent. salt solution, was very beautiful ; it distinctly 
showed the radiating threads of protoplasm stretching from the 
contracted mass to the cell wall, along which nodes or lumps of 
granules were passing outwards with a steady motion, on their way 
back to reform the living protoplasmic membrane of the cell. 
