CONTROL OF MORPHOGENESIS IN PLANARIA. 325 



2. Nutrition. 



My experiments along this line are rather extensive and the 

 results are of considerable interest. I give here only a single 

 series of experiments. The pieces used included approximately 

 the region between the lines 2 and 3 in Fig. I ; fifty pieces were 

 cut from worms which had been fed every 2-4 days for two 

 months (I), another set of fifty pieces from worms of approxi- 

 mately the same size which had had no food for forty days before 

 the experiment began (II). Results are given in percentages. 



Normal. Teratoph- Terato- Aboph- Headless. Dead, 



thalmic. morphic. thalmic. 



1 4 46 6 30 14 o 



II o o 2 10 64 24 



The capacity for head formation is manifestly much greater 

 in the well-fed (I) than in the starved pieces (II). 



3. Temperature. 



Under this head only a single series is given, but the results 

 are characteristic. In this series fifty pieces from similar worms 

 including the region between the lines 3 and 4 in Fig. I were 

 allowed to regulate at each temperature. Results are given in 

 percentages. 



Normal. Teratoph- Terato- Anoph- Headless. Head, 



thalmic. morphic. thalmic. 



28-30 74 22 2 O O 2 



l8-20. 22 40 2 14 22 O 



The death of one individual (2 per cent.) at high temperature 

 was purely accidental. The percentages show the general 

 character of the results. With greater differences of temper- 

 ature greater differences in the results can be obtained. 



4. Alcohol. 



The experiments with alcohol and other anaesthetics present 

 certain complicating factors which will be considered fully else- 

 where, but the effect of alcohol upon the capacity for head for- 

 mation and upon the character of the head formed is readily 

 demonstrated. 



In the series presented here fifty pieces from similar worms, 

 including the region between lines 2 and 3 in Fig. I were placed 



