68 



Willi 



B. H 



erms 



This first experiment was supplemented by a second one a 

 little later (August 28) and carried out on exactly the same plan 

 (series 5, 6). To show the results of this series of experiments 

 more clearly the following table is presented: 



TABLE IV 



Showing results of Feeding Experiments on Lucilia casar, the common green fesh fiy 



Note I — Weight was carefully taken in milligrams. 



Note 2 — Figures in () denote number of individuals weighed. 



Note 3 — The same individuals were weighed in each series except in cases mentioned below. 



Note 4 — See Fig. 6 for relative sizes of imagines. 



EXPLANATION OF TABLE IV 



Series I — The term optimum as here used represents larvae 

 in greatest frequency and also corresponds to the normal frequency 

 of the group which was shown by the weight taken of individuals 

 feeding out of doors, as stated above. This series accordingly 

 forms a convenient basis for comparison in reference to the re- 

 maining series. The normal frequency curves (larvae, pupae and 

 imagines) of Lucilia caesar are based on this series. The feeding 

 period here indicates that the larvae migrated after eating for 

 from 60 to 72 hours. This optimum weight for larvae (mean 

 38.183 mg. and mode 37.00 rng.) represents the point at which 

 the chances are best for pupation and emergence as adults. 

 From this point either way the chances diminish, most rapidly, of 

 course, at the extremes. The pupa cases of optimum forms and 



