46 H. B. FANTHAM. 
In some stained preparations there were somewhat long 
forms with the membrane discontinuous in the centre, where 
a vacuole-like space occurred; the edges of this space were 
sharp, not torn, while the periplast appeared just continuous 
over the gap (PI. 3, fig. 19). 
Further, in living specimens one sometimes sees forms 
vibrating about a node, possibly not central, but I have never 
seen division about such a point actually occur during hfe 
(text-fio. 11). 
It is interesting to add regarding the form shown in PI. 3, 
fig. 19, that each basal granule, at either end of the trans- 
versely dividing form, was—in both cases—itself dividing 
into two, while the whole nucleus showed signs of approach- 
ing division; so that it was likely that the daughter forms, 
themselves produced by transverse division, were in each case 
about to divide immediately by longitudinal division. 
General Note on Division. 
T should like to add the following remarks, from the physio- 
logical point of view, to my discussion of the phases of the 
nucleus during rest and activity respectively, given in the 
preceding section. 
Normal protoplasm is always in a state of slight contrac- 
tion known as “ tonic contraction ’’—which, applied to mus- 
cles, is the so-called ‘‘ muscular tone.” 
Owing to the resistance to the movements of the organism 
by the fluid in which it lives, the migration of protoplasmic 
particles towards the periphery occurs in accordance with the 
physical laws regulating the motion of fluid particles. Under 
such conditions the contraction is increased, and in the case 
of fission resulting it would be rendered more easy because 
under these conditions of increased contraction there would 
be less fluidity in the protoplasm at the periphery of the 
organism than at the centre. , 
Concentration of the protoplasm at the edge would further 
result from the “tone” being increased, and so, with the 
