Notes on S pondylomorum Quaternarium Ehrenh 
never enclosed in a parent vs^all. The first division in this cleavage 
process is as Stein suggested in the general plane of the long axis 
of the cell in most cases. The rule, hotvever,is not absolute. The 
second division also usually approximates the plane of the long 
axis of the cell, and at right angles to the first. This division, hotv- 
ever, is by no means as regular in its course as the first. The 
other two divisions apparently come in with no regularity whatever. 
It is of special interest to note that there is no rounding off on the 
part of the cell preparatory to reproduction. Cleavage takes place 
while the cilia are extended and the colony is motile. It is by no 
means unusual to see an old colony freely swimming about with 
each of its members in a four-celled, or even an eight-celled con- 
dition, and with no evidence of even the beginnings of a separation 
of the mother cells. Division appears to be simultaneous in the 
different individuals of a colony (fig. 7). As was indicated above, 
reproduction takes place in the early morning, and apparently 
goes on with great rapidity during periods of favorable conditions. 
It would be exceedingly interesting to follow the rate of growth and 
frequency of reproduction in these organisms, and determine the 
influence of external conditions, especially the periodicity of light 
and darkness and of heat and cold upon this phase of their activ- 
ities. Nothing of this sort has been attempted in these studies. 
No evidence of sexuality has been observed. 
Spondylomorum shows a number of features which would seem 
to place it in a position somewhat remote from the other colonial 
members of the Volvox group. The entire absence of a gelatinous 
covering for the colony, and the loose union of its individuals, 
and especially the mode of its reproduction by the entire cleav- 
age of the cell, are all wholly uncharacteristic of the coenobic 
forms, and strongly recall some of the simpler unicellular members 
of the order. In fact it would not be hard to conceive of a Spondy- 
lomorum habit having its genesis in the entangling of the cilia of 
a unicellular form like Pyramimonas, a form evidently very near 
the orgin of the Volvocales, and the only member of the order 
resembling Spondylomorum in both lack of envelope and presence 
of total cleavage. Such a conception enables us to see in Spondy- 
lomorum an early step in the evolution of the coenobic habit in the 
Volvocales. 
Granville, Ohio. 
May 3, 1909. 
