578 GEORGE H. BISHOP 



A. Embryonic development, in egg, two days; and multi- 

 plication stage in fat-body, egg, and young larva, one tot wo days. 



B. Growth period. Characterized by one large fat-globule 

 in cell, and irregular cell shape. One to two days, text figure B 

 and plate 1, figure 1. 



C. Fat storage. Development of peripheral ring of globules, 

 with further increase of size. Three days. Text figure C and 

 plate 1, figures 2 and 3. 



D. Nuclear transformation. Cessation of larval feeding, 

 spinning of cocoon, quiescence. Few hours, of sixth day of 

 larval life. Text figure D and plate 1, figures 4, 5, 8. 



E. Development of albuminoid globules. Head of imago 

 forms, prepupa stage. Two to three days. Text figures E and F 

 and plate 2, figures 11, 12, 13. 



F. Globules released. Imaginal form assumed. About six 

 days. Plate 2, figures 14 and 16. 



G. Imaginal fat-body formed, young bee emerges. Last two 

 days of pupation. 



It will be noted that these periods represent not equal periods 

 of time, nor changes of larvae form, but are based on changes 

 within the cells themselves. From three to five substages were 

 examined in the critical periods, D, E, and F. 



b. Technique. The technique employed in the microscopic 

 work was the conventional cytological technique for material to 

 be sectioned. The typical method was as follows: 



A little fixative was injected into the blood space of a larva or 

 pupa with a capillary pipette, to harden the tissues suffi.ciently 

 for further cutting. The larva was then placed under fixative 

 and slit open along the back with fine curved-handled scissors, 

 since the fixatives would not readily penetrate the impervious 

 chitin. Under this treatment the larval stages showed slight 

 distortion in the shape of the cells, due to contraction of body- 

 wall muscles which drew the slit-open larva into a bowed position, 

 with a consequent stretching of the intestinal laj^ers of fat-body 

 cells. The intracellular structure, as checked by larvae killed 

 in hot water, was not materially distorted. Hot water, however, 

 seemed to leave the fat-globules less accurately defined. 



