410 C. M. CHILD 



in percentage in normal and teratophthalmic in the anterior 

 pieces have no greater significance physiologically than smaller 

 differences in percentages between headless and anophthalmic 

 for example. 



In series 368, 327, and 320 starved and fed animals and pieces 

 are of equal size, but in series 638, well-fed large animals are 

 compared with animals originally of still larger size, but reduced 

 by starvation to a small fraction of the original size. 



In all cases the comparative results are the same, the head- 

 frequency being lower in the starved lot. In series 327 the ani- 

 mals of lot II are fed once after eighteen days of starvation and 

 are compared with animals starved nineteen days (I) and heavily 

 fed animals of the same size (III). Here the single feeding of 

 lot II apparently increases head-frequency in A, but not else- 

 where. The head-frequencies are low, even in the fed animals 

 (III) of this series, except in the long pieces (X), because of the 

 small size of the animals, but the difference between starved (I) 

 and fed (III) is very great in B and X. That lack of available 

 nutritive material is not the primary factor in determining the 

 decrease in head-frequency in starvation is indicated by various 

 facts : for example, the slight effect of the single feeding in series 

 327 II upon head-frequency indicates that some other factor than 

 nutritive material is chiefly concerned. These pieces were well 

 filled with food, at least during at least the earlier stages of regen- 

 eration. Moreover, all the series show that starvation and feed- 

 ing do not alter essentially the relation between head-frequency 

 and body-level, although there can be no doubt that in starva- 

 tion nutritive reserves are exhausted first and resorption of the 

 aUmentary tract proceeds most rapidly in the anterior body re- 

 gions. In other words, these regions are most starved, but still 

 show a much higher head-frequency than the less starved regions 

 near the mouth, and even after heavy feeding there is less surplus 

 nutritive substance in the anterior body region, because of the 

 alimentary tract is less extensively developed there than in re- 

 gions about the mouth, yet anterior pieces show the highest 

 head-frequency. In short, it is evident from these data on head- 

 frequency in relation to starvation as well as from those on size 



