bibs ac 7a a ee gy 
As : : ; ; 
Dr. R. Greeff on Autolytus prolifer. 179 
connected with the parent, or immediately after their separation. 
These segments newly formed by gemmation are then, just like 
their tacensiies, developed into a new generation of offspring, 
and thrown off as apparent products of fission, whilst in realit 
they only represent newly developed buds. This first gemmi- 
parous prolification is then again followed at the foremost point 
of separation by a second gemmation, which, after attaining 
maturity, probably gives place to a third, and so forth. In Sylls 
prolifera, therefore, only the first generation thrown off con- 
sists of true primitive segments of the primary animal, whilst 
all the following ones undoubtedly originate for the most part 
from newly developed segments (that is to say, by gemmation). 
I say, for the most part, as according to Krohn’s observations 
(loc. cit. p. 72) it is certainly possible that, in a new budded 
generation, some segments of the primary animal may 
again participate in the division and be thrown off with the 
Reited portion, especially if these segments were previously 
filled with ova &c., and had consequently attained a certain 
degree of maturity. From these considerations, therefore, it 
is clear that the processes of prolification in Syllis and Auto- 
lytus, although apparently so different, scarcely present any 
essential differences when accurately examined. As we have 
seen, both in Autolytus and Syllis, the first offspring are always 
pure sprouts of fission, but the following ones originate in 
both by gemmation. 
Another and different mode of asexual propagation occurs, 
as is well known, in Nats, in which, according to the beautiful 
and careful investigations of Max Schultze*, a segment of the 
rimary animal is thrown off for each new individual, and 
employed in the formation of the latter. This segment is not 
reproduced ; so that, during the continuance of prolification, 
the parent animal loses as many segments as it throws off 
young. Max Schultze justly names this process a reproduction 
by fission, inasmuch as, for every new animal, an original 
| gaia of the mother is absorbed. Nevertheless it should not 
overlooked that from this single primitive joint the actual 
many-jointed animal is produced, only by the development or 
budding forth from it of such a greater or less number of seg- 
ments as may be necessary for the fully formed animal. In 
this way, therefore, every new individual thrown off from the 
primary animal is the product of a pure fission with sub- 
sequent pure gemmation; and thus we have here, again, to a 
certain extent the same point of view for the mode of propa- 
gation as in Syllis and Autolytus, namely the combination of 
* Wiegmann’s Archiv, 1849, p. 295, and 1852, p. 3. . 
