164 SYDNEY .1. HICKSON AND .T. T. '\YADS^Y01^TH. 
base of this arm of the megauucleus gradually becomes con- 
strictedj and at a later stage divides, leaving the knob-like 
extremity as the meganucleus of the gemmula (conf. p. 156). 
In several cases, particularly in specimens from Eiimiug- 
ham, we have observed two of these processes entering into 
the gemmula area, and we have several preparations of young 
gemmuhie with two distinct megauuclei (figs. 16 and 21)' 
When there are two meg’anuclei in one gemmula there seems 
to be a great deal more megannclear substance in proportion 
to the cytoplasmic substance than when there is only one 
meganncleus. A comparison of the different gemmulse with 
only one meganncleus renders it difficult to believe that there 
is any definite relation between the cytoplasm and nucleoplasm 
in gemmule formation. 
One or two, or possibly in some cases more than two 
micronuclei in the vicinity of this swelling increase in size 
until they are about 11 p in diameter. One, or possibly more 
than one of them, becomes spindle-shaped, attaining to a 
size of nearly 14 p in length by 11 p in greatest diameter 
(fig. 19). This microuucleus then divides by mitosis (see p. 
159). 
A\4iile the micronucleus is thus dividing the boundary lines 
of the gemmula are in the process of completing the enclosure 
of the gemmule area. The division of the micronucleus is, 
however, completed, and the daughter-nuclei have consider- 
ably shrunk some time before the area of the gemmule is 
entirely delimited from the pi-otoplasm of the arm. 
It is not possible for us to state definitely that there is any 
constancy in the number of micronuclei taking part in the 
bud formation. 
In the bud that is still in the brood-pouch, shown in fig. 17, 
there is only one micronucleus. In the specimen shown in 
hg. 19 two micronuclei are taking part in the formation of 
the gemmula; in the young form shown in fig. 18 there are 
three micronuclei (only two are drawn, the third being hidden 
by the meganncleus) ; in that shown in fig. 21 there are four, 
and in that shown in fig. 16 there are seven. e have never 
