FLABELLIFERA LIFE-HISTORY 



125 



growth 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. 8 2, 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- 

 mentary canal and 

 mouth-parts. In- 

 deed, only the limbs 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 



FIG. 82. Gnathia maxillaris. A, Segmented larva, x 10 ; 

 B, Praniza -larva, x 5 ; C, gravid female, x 5 ; D, male, 

 x 5. 



