HAZEN: NEW SPECIES OF LOBOMONAS 137 
protoplasmic substance that these motile organisms are able — 
to attain and maintain their specific form. 
In both Brachiomonas and Lobomonas we have noted that 
not infrequently mature cells exhibit a more or less rounded form 
of the protoplast inside of the cell wall, while the latter main- 
tains the typical lobed form as fixed in the formative period. 
Such conditions are not improbably produced by shrinkage due 
to loss of a certan amount of water from the protoplast, accom- 
panied by a tendency to decrease in viscosity of the outer layer, 
in which case, surface tension would tend to bring about a more 
rounded form. In other words, the maturing protoplast might 
be said to show a tendency to revert to what might be considered 
the ancestral form in preparation for reproduction. 
It is a pleasure to acknowledge my debt to Professor R. A. 
Harper for numerous stimulating discussions of problems con- 
nected with morphogensis, and for reading this paper in manu- 
script. 
BARNARD COLLEG 
COLUMBIA UNIVERSITY 
