232 WILSON P. GEE. 



into all the space between the hypodermis and the digestive 

 tract. Specimens killed within an hour after injection and 

 mounted as in the former experiment, showed a slight accumula- 

 tion of the solution in the lumen of the Malpighian tubes. This 

 was even more marked two and a half hours and four hour- after 

 injection, a diffuse blue appearance being then very apparent 

 throughout the cells of most of the tubes. The oenocyles, how- 

 ever, showed no signs of coloration at any of the periods observed 

 nor any evidences of excreting the substance injected. 



Just what the function of these peculiar cells may be it is 

 difficult to say. In no case have I observed in the cytoplasm of 

 any of the oenocytes what could be interpreted as accumulations 

 of solid products of excretion. Their behavior toward methylene 

 blue, and sulphindigotate of sodium would seem to show that 

 they are secretory rather than excretory in function. The nature 

 of their secretion is difficult and practically impossible to deter- 

 mine. Measurements show their greatest size in Platyphylax 

 designatus to be in the pupal stage, and evidences from a purely 

 structural basis seem to point towards the greatest functional 

 activity during the late larval and the pupal stages. Their in- 

 timate relation to the fat-bodies seems vastly more significant 

 than the occasional grouping about a tracheal tube. Their rela- 

 tive increase in size, while of course proportionate to the increase 

 in size of the body, seems to bear a direct relation to the size 

 and development of the fat-bodies. It is also found that their 

 identity is retained throughout the period of metamorphosis. 

 Can it be that their function is the secretion of a substance or 

 enzyme which is of aid to the fat-body in its constructive \vork 

 or is it that their function is, as Anglas (1900) suggests, that of 

 internal glands of a dissociative nature, their secretion serving to 

 aid in the elaboration of products for general nutrition of the tis- 

 sues or for the disintegration of larval cells destined to disappear? 

 These are very pertinent questions, but ones to which a definite 

 answer cannot as yet be given. It seems safe to conclude that. 

 they are internal, ductless, secretory glands, whose function may, 

 in the light of recent progress in the field of internal secretion.be 

 for a long time a matter of conjecture. 



These investigations were taken up at the suggestion of Prof. 



