136 Hazen: NEW SPECIES OF LOBOMONAS 
theless able to maintain for extended periods an elaborately 
eight-ridged or winged prismatic form, and in disintegration 
often break only at one or two points, thus permitting the greater 
body of the protoplasm to remain practically intact, while only 
small streams ooze out. From these observations we are justified 
in concluding that such cells as those of Brachiomonas and Lo- 
bomonas, could we apply methods of microdissection, would be 
found to have protoplasm of a comparatively fluid consistency 
during division, but that local increase in viscosity gradually 
permits the fixation of the characteristic lobed form of the cell. 
When it is recalled that in these two genera the pyrenoids regular- 
ly disappear in preparation for cell division, and are reorganized 
with the maturing of the daughter cells, it will readily be seen 
that in this reorganization, combined with the ordinary processes 
involved in division of cells inheriting differentiation of polarity 
in at least three axes or planes, there is abundant room for the 
play of such metabolic changes as might well account for con- 
siderable differences in viscosity in different parts of the develop- 
ing daughter protoplasts. It is this non-homogeneity of struct- 
ure, involving very likely chemical as well as physical differences, 
which may be regarded as the dominant factor in the determina- 
tion of form in such organisms. From this standpoint, the prob- 
lem as to how this characteristic form may be transmitted in 
heredity does not seem so insoluble as it does on the assumption 
of form determining unit factors in a germ plasm. 
One further point may be emphasized. It is stated by 
Thompson (22) that when ‘owing to some heterogeneity of the 
substance’ the operation of uniform surface tension forces is 
modified so as to result in the production of the ellipsoid cell 
characteristic of yeast, for example, ‘this or any other asym- 
metrical form, once acquired, may be retained by virtue of the 
solidification and consequent rigidity of the membranous wall 
of the cell.’ In the case of the organisms with which we are 
here concerned at least, I am confident, the development of the 
cell wall is not a necessary condition of the maintenance of 
specific form; for the new polyblepharid mentioned above, and 
others of the same group, as well as the gametes of Brachiomonas, 
are able to preserve essentially the same form for long periods, 
in spite of the fact that they are clothed only with a protoplasmic 
membrane of such excessive thinness that it is practically unde- 
monstrable. It is then, owing to relative viscosity in their 
