184 RITTER. [Vou. XII. 
order from the cell mass that forms the last connection between 
the duct and the vesicle. 
e. The Genital System. 
The results obtained from the study on this system are far 
from complete. It is very imperfectly developed in all my 
specimens — so much so, in fact, that I cannot regard as final 
any of the observations made. As already said, my material was 
all procured in one locality, and at the same time, vzz., December 
30—midwinter. It is not at all impossible that when oppor- 
tunity is afforded to examine specimens taken from other 
places, and particularly at other seasons of the year, the sexual 
organs will be found to tell a different story from that intimated 
by the fragmentary facts presented by the colonies so far studied. 
The character of the sexual organs in the adult, already 
described, and the manner of origin of the sexual cells in the 
Botryllus bud, lead us to expect that here also we shall find the 
youngest ova and sperm cells floating free in the body space, 
having been brought hither by the blood directly from the 
parent zooid. That such is the case seems quite certain from 
the facts observed. In several instances I have found ova in the 
blood (Fig. 52, Pl. XVI), but it is noteworthy that in all these 
cases they were in duds far advanced in development. Although 
I have given particular attention to the point I have not yet 
succeeded in finding an undoubted case of sexual cells in a very 
young bud. This seems the more remarkable when it is re- 
membered that the bud becomes fully severed from the parent 
at a very early stage in its development. But the young buds 
examined are far too few to justify the negative conclusion 
that recognizable ova never enter them before their complete 
severance from the mother zooids. Nevertheless the facts 
observed are of a kind and sufficiently numerous to make very 
interesting the several alternative questions which they raise. 
Direct observation shows that in some colonies in which some 
of the blastozooids contain ova and are consequently presum- 
ably capable of sexual reproduction, certain other zooids are 
developed without having received recognizable ova directly 

