SOME PARASITES OF SIMULIUM LARV.E. 



The one exception, however, was that of a larva found on 

 April 17. It was one of the first discovered, in the abdomen of 

 which could be seen, with a dissecting lens, large white bodies 

 floating in the blood plasma. On dis-rrtion the-e bodic- proved 

 to be rounded masses of flagellate spores, t few of which had 

 become di-'-niMjed and were apparently movin- about by their 

 own impetus in the blood plasma. A-, ho\\ ( -\ vr. I ha\ e ne\ er ni 

 any -ub-e<|nem occasion ob-erved MIC:; a movement amon- the-e 

 spon - I .1111 inclined t believe thai thi- was -implv a Bn>\\ man 

 movement, \\hieh I ha\e di-tinctlv re. o-m'/ed in later examina- 

 tion-,. Tliouuh I -arehed carefully for other lar\ a- \\ ith para-ile- 

 in a similar -lage I was unsuccessful. 



In -.-rial -e< lions of parasitized larva- similar effects to th. 

 exhibiied \\hen Mcrmis is present, are noticed in that the fat- 

 bo.lv i^ much redmvd (Plate I\".. Fig. IO) and the -exiial organs 



i onld not be detected, whereas the spinni nd- and mu-cu- 



la i tin- a|i]ai--nil\- remained unaffected. The pata-ite pi-obabk- 

 enters ihe ho-t through the alimentary tract for in all cases of 

 infected larvae i I \\.is found that the mesenteron was di-ioi-te<| in 



one or more places showing distinct hypertrophv as if tin- celU had 

 be< M !'.nll>- initati-d but had healed over again often pcrmitiin- 

 the -pores to pass through into the body cavity Plate IV., I 

 io. , In one case a small colony of "spores" \\ as found in-ide the 

 alimeniaiA tract . but it is <|iiite possible that the-.- h.,d been 

 n;l\ taken in with tin- water, as parasiti/e.l !ar\.e \\ere 

 constantly dxini; in the colony, and an\- material, tloatin^ in 

 the water -uch a- liberated "spores," would be caiijit by the 

 i ( phalic I, in- oi still li\ing larva?. 



In all recorded cases of Microsporidia parasites it ha- been 

 noticed that the "-pores" live, at least during their early -t.i. 

 in-i<le -ome l.od\ ti--ue of the host. An example of thi- j~, \, t 

 be !'< mud in pel >rine < .f -ilk-worm larva. 1 , in which case I he -pinnin- 

 gland- are the main seat of attack. It mn-t be borne in mind, 

 houe\ei, that an attack upon these organs in the larva now 

 under consideration \\oiild, in all probability, iv-nlt in the early 

 death of the host, for it is only by means of the much -tren-t hen<-d 

 silk thread- that the lar\ a i- enabled to maintain in rapid strcain- 

 the perpendicular po-ition \\hich is essential to obtaining food. 



