Notes. 
365 
sensitive to stimulation, viz. Mesocarpus pleurocarpus. The filaments 
consisting of rows of cells were first experimented upon electrically. 
A single induction shock of moderate strength was found to cause a 
splitting apart of the previously united transverse walls of the con- 
tiguous cells along the middle lamellae. In each cell, the two end- 
walls now project inwards towards the centre of the cell in a concave 
manner, so that between each pair of cells of the filament there arise 
a series of double convex lenticular spaces. The rupture does not 
extend to the free surface. 
With a stronger shock so much contraction is produced that the 
cells actually fly apart and a complete rupture is effected. The end- 
walls of each cell are now observed to be slightly convex instead of 
concave. This is a result of the contraction of the freed edges of 
the external walls, which in consequence of the rupture no longer 
maintain their cylindrical form. Each cell now resembles a cylinder 
with its two ends somewhat convex, and its sides very slightly 
contracted in the immediate neighbourhood of their lines of union 
with the ends. As in Mimosa , the breaking is a stronger stimulus 
than the making shock. Similar contraction is obtained with the 
tetanising shock and with the constant current. 
Sudden illumination, sudden rise of temperature (45-50° C.), and 
the stimulus of certain poisons, bring about the contraction and 
breaking apart in the most marked manner. Of the poisons, camphor, 
quinine, strychnine, physostigmine, and strong alcohol were found to be 
exceedingly powerful, with very dilute alcohol no obvious change 
occurred. The strongest plasmolysing reagents did not bring about 
the rupture of the cells, but only the partial separation of the end-wall, 
and if the cells are killed by boiling water, by iodine, or by very 
dilute chromic acid (0-25 per cent.), similar results follow. With 
1 per cent, osmic acid or 1 per cent, chromic acid the cells may be 
killed and fixed with little or no contraction. 
The results with plasmolysis entirely agree with those previously 
obtained in the case of Drosera (loc. cit.) : the protoplasm seeming 
to be partially paralysed, and the whole of its energy apparently ex- 
pended in endeavouring to protect itself from the abnormally rapid 
withdrawal of water. The passive shrinking produced by strong 
dehydrating reagents is essentially different from the active contraction 
arising from normal stimulation, and one may well inquire whether 
the effects produced by plasmolysis at all tally with those vital 
C c 2 
