v FLABELLIFERA—LIFE-HISTORY 125 
erowth of the larva, the range of variation in size of the adults 
being 1-8 mm., and it must be remembered that when once 
the adult condition is assumed growth entirely ceases. What 
it is that determines the stage of growth in each individual 
when it shall be 
transformed into 
the adult is not 
known. The males 
and females differ 
from one another 
so extraordinarily 
that it was for 
long denied that 
they were both 
derived from the 
Praniza larvae. 
This is neverthe- 
less the case. The 
change from the 
Praniza to the 
female (Fig. 82, C) 
is not very great. 
The ovary absorbs 
all the nourish- 
ment in the gut 
and comes to 
occupy the whole 
of the body, all 
the other organs 
degenerating, in- 
cluding the ali- Fra. 82.—Gnathia masxillaris. A, Segmented larva, x 10 ; 
mentary canal and B, Praniza-larva, x5; C, gravid female, x 5; D, male, 
x 5. 
mouth-parts. In- 
deed, only the hmbs with their muscles and the nervous system 
remain. _The change to the male (D) is more radical. The food 
is here stored in the liver, which increases in the male just as 
the ovary does in the female. The segmentation is reacquired, 
and the massive square head is formed from the hinder part of 
the head in the Praniza, the anterior portion with its stylet-like 
appendages being thrown away. The powerful nippers of the 
