A NUTRITIONAL STUDY OF INSECTS 65 



I. La liquefaction cles substances albuminoides resulte d'une veritable 

 digestion operee par certains microbes de la putrefaction. 



II. Les larves de mouches, absorbant exclusivement des aliments 

 liquides, directment assimilables, ont un travail digestif reduit au mini- 

 mum et ne produisent pas de ferments solubles en quantite appreciable. 



III. Les larves accelerent la putrefaction des cadavres en favorisant 

 la pullulation des microbes. 



IV. Les larves se nourrissent aux depens des produits du chimisme 

 microbien; les microbes ne peuvent se developper rapidement que s'ils 

 sont repartis en tous points .par les larves. II existe ontre ces deux 

 agents de la putrefaction une veritable symbiose (p. 369). 



Guyenot does not consider that the food of the larvae may be 

 the microorganisms themselves, and this question is still open, 

 however, unlike the following example* the microorganisms asso- 

 ciated with Lucilia have the function of liquefying the food 

 material. 



Bogdanow ('06) studied the similar case of Calliphora vom- 

 itoria, the flesh fly. The eggs were sterilized by washing for two 

 one-and-one-half -minute periods in 5 : 1000 aqueous HgCU solu- 

 tion and then rinsed in running sterile water and were then placed 

 on sterile media of casein, egg albumin, etc. None of the flies ob- 

 tained was sterile, but was usually associated with a micrococci 

 which Bogdanow beheved was passed through the egg. The lar- 

 vae grew rapidly on casein, egg albumin, albuminoides, etc., in 

 the presence of micrococci and a gelatin-dissolving bacterium, but 

 the flies that emerged were few in number and very small in size, 

 being 'starvation forms.' The larvae were later given the se- 

 lection of fresh or putrid meat, showed a preference for the for- 

 mer, the putrid meat usually killing the larvae. Meats putri- 

 fying in the presence and absence of larvae could be distin- 

 guished by a difference in odor as the micrococcus with which 

 the insect infects the meat liberates ammonia from proteins. 

 The larvae grew normally on meat in the presence of a gelatin- 

 Uquefying bacterimu and the micrococcus. Two factors are 

 therefore necessary for the successful metamorphosis of the larvae 

 the micrococcus from the egg and a gelatin liquefier from the air. 



In 1908 (b) Bogdanow published a second paper on the same 

 subject in which he showed that about 35 per cent of the eggs of 

 the flesh fly are infested with a pure culture of micrococcus. The 



