486 FOOT. [VoL. XIV. 
the stage reached by the eggs in fresh cocoons makes these 
experiments of little value. After preserving a fresh cocoon 
for 14 hours in the compost at a temperature of 21 C., the 
slime-tube was still comparatively fresh and the cocoon con- 
tained odcytes, second order, with sperm attraction-sphere 
and rod. 
Another cocoon, similarly preserved for two hours, contained 
eggs showing exactly the same stage of development. The 
eggs in another cocoon, similarly preserved for three hours, 
had reached the pronuclear stages. In cocoons opened about 
ten minutes after deposition, only an occasional egg has 
remained unfertilized, the rest showing the head of the sperma- 
tozoa just penetrating the egg, or having passed its periphery.” 
The total number of normal eggs? in 100 cocoons was 399, 
or about four to a cocoon, which may serve for a rough estimate 
of the number of normal eggs in each cocoon. At the height 
of the breeding season, however, the average of normal eggs is 
greater ; for towards the end of the breeding season (after 
September 1) a cocoon is often found to contain only one normal 
egg. In the above-mentioned thirty-one freshly deposited 
cocoons, the average of normal eggs is about the same ; thus 
the causes which produce the many structurally disintegrated 
eggs found in each cocoon must be sought in conditions prior 
to the deposition of the cocoons. I have opened 453 cocoons 
and preserved about 1900 eggs, in varying stages of develop- 
ment prior to the first cleavage. It appears to be the rule 
that the normal eggs in each of these cocoons have reached 
very nearly, if not quite, the same stage of development. For 
example, in a cocoon containing 19 normal eggs, 18 are odcytes, 
2d order, the spindle having reached the telophase (z.e., the 
chromosomes appearing as small vesicles) while the sperm rod 
has reached the same stage. Only one of these nineteen eggs 
is an oocyte, 2d order, with the spindle still at the metaphase. 
Again, among 228 eggs taken from 50 cocoons containing 
1 For figures of egg at this stage, see Foot (5), Fig. 3; (6), Fig. to. 
2 For figures representing the last stage, see Foot (5), Fig. 1; (6), Fig. 9; (8), 
Fig. 2. 
8 I use the term “normal” here, merely to designate those eggs that do not 
show any marked disintegration of the cytoplasmic or other structures. 
