Pomona Coi.i.eoe .loi'nNAr. of Kntomoloov 605 



in wliicli tin- iii.ij;j{i>t.s arc always fiiuiid arc rxposcd to tlic air, and consequently 

 collect a larjje amount of foreinii orj{anic matter, such as insects that fall into 

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

 a considerahh- part of the dust in the atmosphere, and, third, plant and animal 

 juices which would Ix- found therein. It is conceivable that the ma);)(ots 

 inif{ht swallow the oil and remove from it tliis forcif^n or);anic matter. This 

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

 and placed in the oil the larva- cluster about them and crawl (Uito them a very 

 short time after the meat has been placed in it. 



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

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

 the well, may be considered quite free from the organic matter nientioneii nl)ove. 

 Hy placing larvw 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 

 he available for the nutrition of the larvip therein. Yet young larvH- have Ix-en 

 so placed and they have j)upated and emerged as imagines. From this it appears 

 that tliey .ire able to derive nutrinu-nt from something beside the foreign organic 

 ni.itter. Other experiments are re|)orted by Dr. Ksterley, such as rearing adults 

 from young larvw placed in oil filtered through a (JoiH'h filter, sterilized and 

 (■.■irefully covered. This. Ii()«e\(r, would jirobjibly not remove all fori'ign organic 

 matter, leaving the plant or .-ininial juices which might be in thi- oil. There is 

 a p.'irartine base in the natural ))etroleum, and it is prob.'ibly this which serves as 

 the fo<Hi of the larva-, in addition to the foreign matter. 



It is very rcniarkabh- that an organism is ;il)le to t.'ike into its .iliinent.'iry e.-m.'il 

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

 ment from it. By a remarkable adapt;ition and physiological changes from the 

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

 part which is nourishing .'ind reject the ))oisonous part. This process, no doubt, 

 is assisted by the large size of the epithelial cells and by the l.-irge :imounl of 

 surface obtained by the length of the ventriculus. 



To show the effect of petroleum on an un;id:ipted alin\enfary can.-il some of 

 the oil was forced down the mouth of .-i largi- tomato worm. The worm showed 

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

 this tiuu' 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, :is reported by Mr. .Sh.afer. to whom further reference will be made 

 sliortly. 



I'liat this pliysit)logieal ;ula)itation of the digistive epithelium to poisons is 

 very remark.able, is shown further by the following ex|)eriment. .\ eonsidernbic 

 amount of white, powdt'red arsenic was thoroughly mixed with a small dish of 

 petroleum and four larva- pl.aced therein. They were watched closely for a long 

 time and appeared to .act perfectly normal, all the while swimming al)ouf and 

 feeding as in pure oil. .Vfter three days one died very gradually, the other three 

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

 an extraonlin.arv test is obvious. 



