96 W. M. Smallwood 
development is interesting and raises the question of the signifieance 
of these structures and also the further question: Are we to regard 
such phenomena as found in the eggs of Chaetopterus as entirely 
the result of the artificial treatment? 
In Haminea solitaria chromosome vesieles are present in the 
early prophase of the first maturation. In this molluse it does not 
matter whether the eggs have passed into the oviduet and have been 
fertilized, or are still in the follieles of the hermaphroditie gland, 
maturation begins in all as soon as the first is deposited. The pe- 
netration of the sperm is not the force which starts the mitotie 
phenomena but apparently it is the contraction of the body in foreing 
the eggs to the outside which ineites the formation of the maturation 
figure. It frequently happens that one may find in the ovotestis of 
H.solitaria, if fixed when deposition is in progress, eggs in the 
metaphase of the first maturation figure in the most distant follieles. 
Several hundred eggs all in the same stage are found, indicating 
that these changes started in each at the same time. A study of 
these eggs which have just begun maturation reveal chromosome 
vesieles wbich are to contain or do already enclose a single chro- 
mosome. 
In the earliest stages these vesieles lie at the ends of the spindle 
fibres. Irregular in shape, they may contain several or but one 
chromatin mass. The number of vesieles which arise corresponds 
to the number of chromosomes. As they enlarge each becomes 
elliptical in outline, the chromatin inereasing in quantity at the same 
time. A more extended study of these stages seems to indicate that 
their origin is in the linin. When these vesicles first appear, they 
are in their largest state although not as definite or as thick walled 
as in the metaphase (Fig. 12, Plate 3). The chromatin in the early 
prophase is in the form of small granules located at the nodes of 
the linin meshwork. While it is possible that the formation of the 
vesieles may involve a process of vaculolation around the chromatin 
yet no differenee in the ehromatin located at the nodes of the linin 
fibre and that enclosed in the erudely formed vesicles can be noted. 
Whenever the chromatin is present along the walls of these vesicles, 
it can be readily distinguished by any of the basie stains. As the 
linin disappears from the germinative vesicle in the early prophase, 
the number of vesicles inereases; probably, however, a portion of 
the disappearing linin, contributes to the formation of spindle fibres 
and sphere substance as in Crepidula. The evidence in H. solitaria 
