Mr M*Lean, Amatosis in the Parenchyma of Water-Plants. 381 
young stems than in older ones; they are much more frequent in 
sections taken close to a node than in those taken about the middle 
of the internode. They are also more frequent in the inner zones 
of the cortex, and the frequency diminishes towards the periphery 
of the stem. 
The appearances presented are somewhat peculiar. Irregu- 
larity of outline is a well-known characteristic of nuclei in amitosis 
and these are no exception to the rule. The prevailing form, 
however, is an elongated spindle-shape, often twisted until it 
appears sigmoid. Sometimes the nuclear outline is amoeboid, 
the nucleus appearing to send out pseudopodia, its own diameter 
or more in length. These pseudopodia are distinctly acute and 
taper off insensibly into the cytoplasm. They are not mere lobes. 
Paired nuclei in cortical cells of Hippuris vulgaris. In all cases the 
two nuclei lay in the same focal plane. x 240. 
So common is the sigmoid form, resembling in outline the diatom 
Pleurosigma, that even when stages of actual amitosis are not 
found the existence of amitosis may be inferred from the nuclear 
form in the tissue under observation. Sometimes the length 
of these nuclei is as much as ten or twelve times their diameter. 
It must be noted in conjunction with the last remark that cell- 
division does not follow nuclear division for some time, so that the 
sigmoid forms above referred to are almost always to be found 
associated together in pairs in the same cell. Rarely three may 
be met with in one cell, and not infrequently the nuclei in each 
pair may be twisted round one another, although not in any way 
united, recalling the appearance presented by the alga Raphidium 
which both resembles these nuclei in form and in the way which 
