. The Cambridge natural history. Zoology. 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.

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. The Cambridge natural history. Zoology. 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. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company