394 THE AMERICAN NATURALIST. [Vor. XXXIV. 
IV. MATURATION AND FERTILIZATION. 
Under these heads I shall give at this time only the merest 
synopsis of my observations, for there are many points yet to 
be worked out in detail, and to these I shall give special atten- 
tion in a later paper, which is, however, well under way and 
may, I trust, appear within the near future. 
As Smallwood has pointed out (99), and as Doflein ('96) has 
also shown for Tubularia, and as I have found in Parypha, the 
ova grow within an ovarian mass of primitive ova by the con- 
sumption of their fellows, nuclei of which may be seen in all 
stages of degeneration, both about and within the growing 
eggs. In Parypha the most perfect illustrations of degenera- 
tive metamorphosis and amitotic division are shown, and in 
this form they are not wholly disintegrated during the process 
of segmentation of the egg, nor even till after at least the 
ectoderm of the larva is very clearly established. 
. As the egg grows the nucleus migrates toward the periphery, 
becomes very indefinite in form, and also seems quite indiffer- 
ent to ordinary staining processes. In only a few cases have 
I found from surface preparations, and in observations upon 
the living egg, any clear examples of polar bodies. However, 
the fact that the ova are devoid of membrane and are peculiarly 
opaque would naturally obscure or render quite transient these 
bodies. The ova are of relatively large size, varying from 
.4 mm. to.5 mm. in diameter, and heavily yolk-laden, and, as 
already indicated, vary in color from a creamy white with faint 
trace of pinkish hue to a clearly orange color. 
Fertilization occurs very soon after the ova are discharged 
from the medusa, and hence only external, unless, as indicated 
in another part of the paper, where, after the velum is ruptured 
as well as the mesentery suspending the egg, fertilization 
may readily take place within the bell cavity. A number of 
experiments and observations have demonstrated this quite 
conclusively. Artificial fertilization is quite easy and can be 
controlled at will Very soon after extrusion of the egg, 
sperms may be seen surrounding it in great numbers, in some 
cases completely covering it and adhering for some time. The 
