445 



An examination of Table II shows that there is a very great variation 

 in the catalase content per unit of larval weight. One cause of this 

 variation was undoubtedly the difference in the age of the larvae. Food, 

 conditions of the environment after leaving the apple, and individual 

 variation are other possible causes. It seems reasonable to suppose that 

 there is a gradual increase in catalase content up to the time of pupation. 

 This is not proved by these experiments, but the general results seem to 

 indicate that it is a point well worth further investigation. Experiments 

 are planned for this purpose. 



While it is always a question what any given larva used in the 

 experiment would have done if left alone, experience with several thou- 

 sands of larvae leads to the belief that the general appearance of an indi- 

 vidual when the pupation time arrives, indicates whether it will pupate 

 or not. The plump, healthy-looking individuals nearly all pupate, while 

 those which appear thin and shrivelled remain dormant and eventually 

 die without pupating. The plump, well-conditioned larvae always gave a 

 high catalase content, r),000 cc per gram or more, while those which 

 appeared dried and shrivelled gave a low catalase content, usually about 

 3.0U0 cc per gram. In the absence of better criteria by which to tell those 

 larvae which would pupate from those which would remain dormant, it 

 is justifiable to suppose that, if the catalase content increases as the larva 

 advances toward the time for pupation, then the catalase content may be 

 a determining factor or at least a correlated factor in the dormancy. 



Table III shows the results obtained from nine larvae which had 

 been kept over winter in a cool place and subjected to a flow of dry air. 

 Five of these appeared plump and healthy and gave a high catalase 

 content ( Nos. 1, 4, 5, 8, 9). The other four were shrivelled and gave a 

 low catalase content. A control set, which was kept and allowed to 

 pupate, showed that abotit one-half of the lot would probably have 

 pupated. 



Table III. Catalase Content of Larvae Kept Over Winter in Cool Dry Air. 



Weight of larva 

 in gms. 



Gas obtained 

 in cc. 



Gas per gm. of 

 larval weight. 



