536 REPORT —1883. 
with ammonia-carmine, the separate protoplasts give evidence of various degrees 
of inter-relation, the most important being (1) knob-ended protoplasmic prolonga- 
tions, their knobs having been firmly adherent to the middle lamella at the base of 
a pit (‘closing membrane’), knob-ended threads from contiguous protoplasts being 
very commonly attached to opposite sides of the same closing membrane, and the 
membrane often showing cross-striation between the knobs; (2) very much less 
common fine unbroken threads passing from one protoplast to another, and joining 
them, therefore, together. These latter he had described and figured in the cortical 
tissue of Ilex aquifolium and Asculus hippocastanum, the pulvinus of Prunus 
Laurocerasus, and the winter-bud pith of Acer Pseudoplatanus, in which alone, out 
of 22 plants investigated at different times and in different parts, he had found 
them. The author believes that most such threads would be broken in the process 
of preparation, but points out that rarity would be no barrier to their action, as a 
single thread passing from a cell to each of its impinging neighbour cells could 
produce a perfect unity of the vegetable organism. 
Discussing the general objection formulated in the English translation of the 
fourth edition of Sachs’ ‘Lehrbuch der Botanik, p. 788, that turgidity, and 
consequently the growth dependent on turgidity, would be impossible with cells 
having open pores in their walls, inasmuch as the smallest hydrostatic pressure of 
the cell sap would be equalised by filtration through the pore, the author points out 
that were the pores only to communicate from cell to cell, and assuming that Sachs’ 
contention that filtration would readily take place through them is correct, the only 
effect of such pores would be to equalise the turgidity of the inter-communicating 
cells, and, therefore, to equalise the growth resulting from that turgidity. 
As to the action of such pores if they communicate with the intercellular 
spaces, or with the exterior, again assuming that free filtration through them is 
possible, the author answers :-—firstly, that such openings would not be expected to 
communicate commonly with the exterior or with other than neighbouring cells, as 
where they occur they have probably been in existence from the earliest phases of the 
cell’s life, and the formation of an intercellular space would probably close them, 
and also that deep pits with closing membranes commonly do not occur in such 
places. Secondly, bearing in mind the case of the filaments from Dipsacus sylvestris 
to which Fr. Darwin has drawn attention, and the frequency of cilia projected 
through cell walls in the Thallophyta, the author thinks it by no means proved that 
such cells cannot become turgescent ; and finally asks how the sieye-tubes would 
withstand the pressures they have to bear if their sieve perforations would destroy 
turgipotence. He points out that in all these cases the cell sap would still have to 
pass through protoplasm completely filling the pore; that when the protoplast is 
in its normal position lining the cell wall, this core of protoplasm filling the pore 
would offer great resistance to a bodily passage of the cell sap promoted only by 
the differential pressures of the cells, while molecular passage would take place 
more easily in other parts of the cell; and, on the other hand, in the plasmolysed 
cell, filtration through the cell wall would go on too readily to admit of the use of 
the still ‘ plugged’ pore. j 
The author then passes on to discuss the possible physiological action of the 
connecting threads, suggesting that an irritant applied to one cell would cause its 
protoplast to contract, the threads to be stretched, communicating the stimulus to 
the surrounding cells, these onwards to the next outer zone, the contraction thus 
affecting a gradually and rapidly widening area. The whole tissue would then 
contract by the outward filtration of the cell sap. 
He further suggests the possibility that the cells may be made forcibly to 
contract somewhat through the agency of those threads (‘ knob-ended’) which do 
not pass through the walls, but retain a hold on the middle lamella at the closing 
membrane. Knob-ended threads also could transmit impulses. 
Finally he brings forward the hypothesis that protoplasm may be endowed with 
spontaneous expanding powers, similar to its powers of contraction, powers which 
the known nature of protoplasmic movements renders not unlikely. These expand- 
ing powers might be exerted at some one point or in some one direction, and thus 
define the tendency of the cell to assume a particular form. 
