206 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and in some of the branches leading from them. It continues for a time 
and then ceases without apparent reason. The rate of movement varies 
greatly, and is quicker than the rotation of Nitella or the circulation of 
Tradescaniia ; 3*3 mm. per minute was measured. 
The author does not find, in the phenomena observed, any support 
for the theory of an autonomy of the vacuoles or of a special vacuolar 
membrane, advocated by De Vries and others. Return currents were 
occasionally seen, always occupying the periphery of the hyphal cavity ; 
they never carry vacuoles. He considers the origin of the movement 
to be rather in osmotic absorption and exudation of water than in the 
vitality of the protoplasm itself. 
Relations of Chloroplastid and Cytoplasm.* — Dr. A. J. Ewart con- 
tests the adequacy of the bacterium method employed by Kny and 
Kolkwitz to detect the assimilating energy of chlorophyll-grains. He 
states that the inhibition of the power of assimilation in chlorophyll- 
bodies contained in a living cell, which may persist for a time after the 
injurious agency has been removed, is due to a pathological condition 
which may be induced in the chloroplastids of many plants by the pro- 
longed operation of almost any injurious agency of sufficient intensity to 
depress the functional activity of the chlorophyllous cells to the lowest 
possible ebb consistent with the preservation of vitality. From this 
pathological condition recovery may or may not be possible. 
Histology of the Cell-wall.f — Mr. W. Gardiner has pursued his in- 
vestigations on this subject, especially in relation to the threads of pro- 
toplasm which pass from cell to cell. He has been able to demonstrate, 
in a large number of cases, the presence of threads of undoubtedly pro- 
toplasmic nature, often of exquisite delicacy, which pass in large numbers 
through the walls of adjacent cells, not only where they are thinned by 
the presence of pits, but elsewhere also. He thinks there can be little 
doubt that such connecting threads occur universally in the cells of all 
the tissues of all plants. From this arises the fundamental conception 
that the plant-body must be regarded as a connected whole. It goes far, 
also, to explain the transmission of impulses and of nutrient material 
from one part of the vegetable organism to another. 
In the case of pitted tissue, the author finds the pit-closing membrane 
to be invariably traversed by what he terms “ pit-threads.” But the 
threads are by no means confined to the pits ; they often perforate the 
walls of the cells themselves, when he calls them “ wall- threads.” When 
pit-threads and wall-threads coexist in one and the same cell, the former 
are stouter and more readily stainable than the latter. The pit-threads 
are necessarily arranged in groups, and in each group the threads are 
arranged in bundles. The threads appear to be present ah initio ; it 
would seem that in a given cell the whole system of connecting threads 
arises at an early stage, and that no subsequent development occurs. 
The theory of a system of open pits connected with one another is alto- 
gether discarded by the author. 
The following is a list of the tissues in which the author has at 
present detected these connecting threads : — Cotyledons of Trojpseolum 
L. * Bot. Centralbl., Ixxii. (1897) pp. 288-96. Cf. this Journal, ante , p. 101. 
f Proc. Roy. Soc., lxii. (1897) pp. 100-12 (8 figs.). For Technique, see p. 240. 
