222 R. W. GLASER. 



chanical forces of cell division being absent, they are not able 

 to be carried far from their starting point. Moreover, since 

 there are no other growing tissues between them and the ecto- 

 derm, except a few small muscles and connective tissue, they 

 are not pressed or shoved out of the way very much, and are so 

 able to retain their original position. I am inclined, however, 

 to the former view, that there is a definite functional relation 

 between these glandular cells and the tracheae. 



That the cenocytes in Zeuzera pyrina are so large is probably 

 due to the prolonged larval stage of this insect. As previously 

 stated, it remains a larva three years, during which time it 

 eats ravenously, and grows very heavy, acquiring an enormous 

 amount of fat. Naturally, since it eats so much, and stores up 

 so much reserve food, it has a great deal of material to oxidize, and 

 consequently needs a large supply of oxidizing enzymes. A com- 

 parison with other insects would lead me to this view, for those 

 having a short larval stage like the Dipteran larvae, have much 

 smaller cenocytes in comparison with the remainder of the body 

 than forms with a prolonged larval life, like the phryganeid larvae, 

 for example. 



Before closing, I wish to express my thanks to Professor 

 William M. Wheeler for the kindly advice and encouragement 

 which he has given me at all times. I also wish to thank my 

 father, Dr. Charles Glaser, of Baltimore, for many valuable 

 technical points. 



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