SOME PARASITES OF SIMULIUM LARV.E. 313 



gave the following results: Xumber of larvae present 174; number 

 of parasitized larv;e 41. This means that in this particular 

 locality about 23.5 per cent, of the larvae would be unable to 

 mature on account of tin- Mermis parasite. 



The species living in the Stony Brook Reservation was found 

 to be para-it i/ed only to the extent of some 3-4 per cent. A few 

 6". hirtipes were also present in the same stream and were para- 

 -i i i/ed only to the same extent, so it is probable that thi< smaller 

 attack wa- not dm- to tin- host's belonging to a different species. 



CAUSI "i IHE RETARDATION \' mi; HISTOBLX-I-. 

 In order to arrive at some definite conclusion as to \\liv the 

 hi-tobla-t - ol ,1 parasitized larva should not develop normally, 

 it will In- o| advantage to review briellv xuiu- of tin- theorie- 

 which have been advanced to explain the normal development 

 ol ihe-e <\\~< -,, and at tlie same time to consider the fact-, which 

 ha\e In- n brought to li-ht by the study of several cases n<>\\ on 

 id in u liich the di-.cs have developed with abnormal rapidity. 

 tlm- prodiK in.; larvae \\hich p - character- that normally do 

 pot make their appearance until the pupal or adult condition is 

 reached. This abnormal condition ha- been termed "pro- 

 thetely" bv Kolbe (1903). l For the abnormally retarded con- 

 dition as produced in the Sinuilinnt larvae by the pre-ence of 

 M,->n:is I should like to surest the word " metal heteK ." 



The earlie-i re|)ort of prothetely was made by Ilexnion- 

 '96 . In tip larv;p of Tencbrio nwlit< \. . \\en- found which, 



ulien matuic. |'ro\rd to be abnormally developed as follo\\-: 



I The meso- and meta-thorax possessed expanded lateral por- 

 tion- ol the termite-, \\hich resembled the wing-pads oi the pupa, 



though the\ \\eie not folded under the body as in the latter, 

 but \\ere direcit d I'.n kuards. 



2. The antenna- had additional incompletely segmented joints, 

 ihu- a|)pn>achin- tin- i i -jointed adult condition. 



,v The abdominal termite- \vere modi tied SO that they resembled 

 the termite- of the |)U|)al abdomen. 



The>e lar\,e wen- rai-ed in the meaUvorm cultures of the 



' \lpotf(iv. tn run before, .ml ^'\'->5. th.- 

 \\>Tat>(tv, to run Ix-liiml. .in-1 -f\os. tin- 



