332 WHITMAN AND EVCLE SEH VIlia [VoL ik 
disc seen in the meroblastic egg of the teleost. One might 
say that the calotte represents a nascent blastodisc, —a blasto- 
disc 72 statu nascendi, so to speak. It differs from the blas- 
todisc, as seen in pelagic teleostean eggs, chiefly in not 
containing the whole, or almost the whole, of the material to 
be used in the formation of the embryo. The Amia egg is 
holoblastic, but represents an advance upon the condition seen 
in the egg of Acipenser, in the direction of the meroblastic 
egg of the typical teleost. 
At this stage one or more irregular cavities are found in the 
upper hemisphere, between the centre of the egg and the 
calotte. One of these is shown in Cut 2. Just when and how 
these cavities arise we cannot say, but they are present in the 
first, as well as the later stages of cleavage. Sooner or later 
they become continuous with cleavage grooves, and in many 
cases unite in a common cavity. As these cavities appear in 
eggs prepared in different ways, collected in different seasons 
from various nests, it seems certain that they are not to be 
considered as artificial. 
Second Cleavage. — The two grooves of the second cleavage 
usually begin at the same point of the upper pole and extend 
meridionally at right angles to the first groove (Figs. 4, 22, 23). 
Their progress is essentially the same as that of the first. In 
the egg shown'in Fig. 4 these grooves appeared at 8.58; at 
9.40 they had extended slightly beyond the margin of the 
calotte, and three to four hours later they had completely 
encircled the egg. 
Variations in the formation of these grooves are not uncom- 
mon. The point of origin may be at a greater or less distance 
from the pole (Fig. 10). Instead of a right angle, acute and 
obtuse angles may arise, the grooves crossing in the form of an 
X (Fig. 11). Again, the furrows may not arise at the same 
point, but at points more or less widely separated, as in Fig. 12. 
They do not always begin at the same time; one may precede 
the other by a considerable interval, reaching near the lower 
pole before the other has passed the equator (Fig. 14). Ovcca- 
sionally the two unite at the lower pole to form a continuous 
line running at right angles to the first; at other times they 

