482 ZOOLOGY. 
of the parts that had been divided off. It becomes an interesting 
question how often such division could take place in any indi- 
vidual ; without being able to pronounce any positive opinion on 
this point, Lütken inclines to the belief that up to a certain age 
it can be repeated several times. Allowing that the faculty of 
regeneration is very great among the ophiuroids (a disk of an 
ophiura deprived of all its arms will sometimes under favorable 
circumstances renew them all), still the phenomenon witnessed in 
Ophiothela differs from a mere casual renewal of lost parts of an 
accidental lesion; there is a regularity and symmetry about it 
which certainly points to a true natural spontaneous division hay- 
ing for its object the multiplication of the individual. It must not 
be forgotten, moreover, that Profs. Steenstrup and Sars have ob- 
served the same phenomena in certain small ophiuroids with six 
arms, especially among species of the genus Ophiactis that live in- 
tertwined among corals and sponges, nor that the truth of their 
observations has been confirmed by Lütken himself. In one or 
two species of another genus, Ophiocoma (O. pumila), the same 
thing occurs ; in these instances it becomes clearly apparent that 
in young individuals only this agamic form of reproduction takes 
place, and that with the adult forms the results of the division are 
truly sexual. Similar phenomena have been remarked in certain 
Asteride, notably in Asterias problema Stps., and in some allied 
species described by Verrill, as well as in Linckia ornithopus and 
Ophidiaster cribrarius. Lütken is of opinion that though there 
are many cases where the spontaneous division is merely gemma- 
tion more or less disguised, there are likewise many instances in 
which it is, so to speak, simple division and nothing else. In the 
ease of the ophiuroids and asteroids he inclines to think it a 
normal form of multiplication, which takes the place of gemma- 
tion. It would have a near relationship to the power of regen 
ration on the one hand, and to that of gemmation on the other ; 
and while it may not always be possible to clearly define the 
exact limits of these ‘“ powers,” it is convenient to preserve to 
“ Schizogony ” an independent place among the different forms of 
agamic multiplication. The classifying of the phenomena above 
alluded to as occurring in the ophiuroids and asteroids in the cate- 
gory of “‘Schizogony,” conclusively indicates, in short, that there 
is in this spontaneous division something altogether different from 
gemmation. The following general propositions are laid down by 
