Pomona College Journal of Entomology 695 



in which the maggots arc always found are exposed to the air, and consequent!}' 

 collect a large amount of foreign organic matter, such as insects that fall into 

 the oil and die, bits of floating organic particles, bacteria, etc., which compose 

 a considerable part of the dust in the atmos))here, and, third, plant and animal 

 juices which would be found therein. It is conceivable that tiie maggots 

 iniglit swallow the oil and remove from it this foreign organic matter. This 

 view, moreover, is strengthened by the fact that when bits of raw meat are crushed 

 and placed in the oil the larvae cluster about them and crawl onto them a very 

 short time after the meat has been placed in it. 



We encounter a difficulty, however, in this regard, because of certain experi- 

 ments that have been carried out by Dr. Esterley. The oil, as it comes fresh from 

 the well, may be considered quite free from the organic matter mentioned above. 

 B\' placing larvae in such oil and keeping the oil carefully sterilized and covered, 

 it would seem that nothing but the actual organic components of the oil itself would 

 be available for the nutrition of the larvw therein. Yet young larva; have been 

 so placed and they have pupated and emerged as imagines. From this it appears 

 that they are able to derive nutriment from something beside the foreign organic 

 matter. Other experiments are reported by Dr. Esterley, such as rearing adults 

 from young larvae placed in oil filtered through a Gooch filter, sterilized and 

 carefully covered. This, however, would probably not remove all foreign organic 

 matter, lta\ing the jjlant or animal juices which might be in the oil. There is 

 a p.iraffine base in the natural petroleum, and it is probably this which serves as 

 the food of the larvae, in addition to the foreign matter. 



It is very remarkable that an organism is able to take into its alimentary canal 

 such a substance as petroleum and not only survive, but actually derive its nutri- 

 ment from it. B}- a remarkable adajjtation and physiological changes from the 

 normal the epithelium of tlie digestive canal is able to extract from the oil that 

 part which is nourishing and reject the poisonous part. This process, no doubt, 

 is assisted by the large size of the epithelial cells and by the large amount of 

 surface obtained by the length of the ventrieulus. 



To show the effect of petroleum on an unadapted alimentary canal some of 

 the oil was forced down the mouth of a large tomato worm. The worm showed 

 signs of "sickness" in a short time, and died after about four days. During all 

 this time it remained in a contracted form, although it was offered fresh leaves 

 to feed on. Similar results were produced on a large caterpillar by feeding it 

 kerosene, as reported by Mr. Shafer, to whom further reference will be made 

 shortly. 



Th.-it this ))]iysiologieal adaptation of the digestive epithelium to poisons is 

 very rem.irk.ihle, is shown further by the following experiment. A considerable 

 amount of white, powdered arsenic was thoroughly mixed with a small dish of 

 jietroleuin .•iiid four larva' jjlaced therein. They were watched closely for a long 

 time an<l a|)peared to act perfectly normal, all the while swimming about and 

 feeding as in pure oil. After three d.-iys one died very gradually, the other three 

 lived for four days before succumbing to the poison. The significance of such 

 an extraordinary test is obvious. 



