PLATE 4 



EXPLANATION OF FIGURES 



12 Portion of a cross-section of the seventh abdominal segment of a larva, 

 taken one-half day before pupation. B, basement membrane; F, fat-sphere; 

 H, hypodermis; LL, large leucocyte; PC, primary cuticula; SC, secondary cuti- 

 cula; SL, small leucocyte; T, trachea; U, undifferentiated cells of the light-organ. 



13 Portion of a cross-section of the seventh abdominal segment of a pupa, 

 taken one-half day after pupation, to show a little later stage than figure 12 in 

 the formation of the light-organ. C, cuticula; F, fat-sphere; H, hypodermis; 

 LL, large leucocyte; M, muscle; (SL, small leucocyte; T, trachea; IJ , undifferen- 

 tiated cells of the light-organ. 



14 Portion of a cross-section of the seventh abdominal segment of a pupa, 

 taken one day after pupation. It represents a slightly later stage than figure 13. 

 For labels see figure 13. 



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