EFFECTS ON THE HIGHER INVERTEBRATES 57 



29). The secretory granules undergo a progressive absorption, and the "chro- 

 matoplasts" (chromidial apparatus, etc.) undergo regressive changes. This 

 phase occupies about two months. Then follows (2) the phase of degeneration, 

 with syncytial cell-fusion, karyorrhexis and pycnosis. These are destructive 

 changes leading to necrosis (Fig. 30). 



If the ordinary room temperature (i7°C.) is increased to 32°C, the inanition 

 changes usually requiring four months are attained in three weeks. Changes 

 very similar to those during inanition appear also as a result of functional 

 exhaustion at the end of the normal egg-laying period. No structural changes 

 occur in the gland during hibernation, unless artificially prolonged. In a snail 

 richly fed for two days after five months of starvation, evidences of recuperation 

 were found already beginning in the gland cells. 



Pelecypoda. — Sorg (1805) noted death from starvation in 18 days in My a 

 ftictorum. Mead Coo) made a few incidental observations indicating that the 

 relations of growth and nutrition in the clam and oyster are similar to those 

 already metioned for the starfish. Maas ('07, '12) noted that in Ca-free water 

 the calcareous substance in the shells of young mussels (species not stated) 

 may be resorbed without injury to the soft parts. Schultz ('08b) found that 

 during inanition, in filtered water, the young mussels Mytilus (like the starfish) 

 cease to grow, but undergo no "reduction" to embryonal type and die in about 

 three weeks. Sections show no important changes. "Die Verdauungsorgane 

 erleiden natiirlich wahrend des Hungers die ersten Veranderungen, und die 

 Zellen der Leber, z.B., verschmelzen und bilden ein Syncytium." 



TROCHELMINTHES 



The effects of inanition in the rotifers (wheel animalcules) have been studied 

 chiefly in their relation to reproduction and sex. Leydig noted that when 

 rotifers are kept a few days in water without food, the ovary shrinks, and the 

 granular yolk-mass almost entirely disappears. All such individuals produce 

 winter eggs. Regarding the effects of nutrition upon sex, he concludes: " Wenn 

 wir sehen, dass bei Aphiden, Daphniden, Rotatorien, Mannchen unter dem 

 Einfluss allgemeiner Ursachen, als da sind Nahrung, Warme und Kalte, zum 

 Vorschein kommen, so haben wir einstweilen einen Anhaltspunkt zu der Ver- 

 muthung dass die Differencirung des Geschlechts auch in anderen Gruppen 

 ahnlichen allgemeinen Einwerkungen unterworfen sein konne." 



Nussbaum ('97) concluded: "Bei Hydatina senta bestimmt wahrend einer 

 gewissen Entwicklungsphase die Ernahrung das Geschlecht des ganzen Geleges 

 eines jungfraulichen Weibchen. Wird das auskriechende Weibchen bis zur 

 Reifung seines ersten Eies gut ernahrt, so legt es nur weibliche Eier; wird es bis 

 zur Geschlechtsreife mangelhaft ernahrt, so legt es nur mannliche Eier. Vor 

 und nach dieser Periode hat die Ernahrung auf das Geschlecht keinen Einfluss." 

 Nussbaum's results were comfirmed by Lenssen ('98), but opposed by Punnett 

 ('06), who concluded that the sex is due to internal factors, unaffected directly 

 by food or temperature. 



