220 The American Naturalist. [April, 
the anterior and posterior poles of Volvox. It is equally re- 
markable that none of the extant figures of Volvox correctly 
represent the definite relation of position of the " eye-spots " 
to the axis of rotation of the whole caenobium or colony and 
the flagella of the cells. 
The facts which are here noted in regard to Volvox serve 
rather to strengthen the claims of zoologists to this singular 
organism, which is actually found to combine features of the 
vegetable and animal world in its physiological activities. 
While its respiration, chlorophyl, and modes of reproduction 
seem to affiliate it with the plant kingdom, the obvious differ- 
entiation of a system of anterior organs, which refuse any 
other identification than that of sensiferous structures give it 
claims upon the animal kingdom. If we look upon Volvox 
as a form which has permanently not passed beyond the ideal 
blastula stage and which lies near the point of divergence of 
Metaphyta from the Metazoa we shall probably assign it to 
nearly its true position. It has many interesting features, one 
of which is its blastula-like form ; its cells embedded in cellu- 
lose and united by protoplasmic bonds into a sort of syncy- 
tium ; its differentiation of a directive anterior empty pole 
apparently provided with a more specialized sensory apparatus, 
as pointed out above, and of a posterior reproductive pole or 
hemisphere, in the cells of which the supposed sensory appar- 
atus is so reduced in importance as to have been nearly 
suppressed. Carrying our reflections farther, we may be per- 
mitted to suppose that conditions of organization may and do 
exist, as evidenced in Volvox as here described, in which 
structures and functions may be manifested, which we must 
regard as sensiferous, yet in so low and generalized a form in 
a blastula-like type, that we find the organs developed in every 
cell, the only evidence of differentiation or specialization obtain- 
able being that which occurs at that pole of the blastula which is 
habitually brought into the most important or dangerous rela- 
tion to the environment. The end result being that a type com- 
parable to the hollow blastula has the sensiferous apparatuses of 
the cells at its constant anterior pole better developed than in 
