Dominion En tom ological La borato r y, Kamloops . B , C , Th e fo Jl o \\'ing a r e Il o tes on a ,;e ri es of ex p erim ellt s that ha\' e bee ll condu c ted al o ng s uch li n e,; t e nding t o cunt ribu te tCJII'a rd s a better kn o wl edge of ti c k f ee din~' . ib \'ary ill g rates and it s r elati o n t Il di sease. Th ey are m e n tioned at t hi s dat e as suhj ec ts of gen e ral int e rest , and t o sa\'e cOllfu s io n have iJ ee n g ro up ed acco rding t o th e \'a ri o u s proced ur

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... s that have bee n fo ll owed. The ir relatio n s hip and bearing t o ea ch ot h e r is withh e ld until su ch time as co nclu s ion s m ay be drall' n fr 0 111 th e co mbin ed r es ul t s o f th ese and o ther ob se r vat io n s. Infesting Experiments I ) The re la ti o n uf t he rate of tick fee din g t o tick paraly s is was menti o n ed in th e writ e r 's last r epo rt t o th is suc iet y (1). T ll th e in -"tanc es of va ry in g r ates of en gor gem ent th en g iv en , m av be add ed anoth e r s trikin g ex ampl e. A se ri es of ti cks (Dermacentor andersoni ) o btain ed fr o m l~ay l e i g h. 13. C. o n Ap ril 30, ] 936 were placed o n a s he ep u n r\ ug u s t !) . .-\ t th e end of !) day s, ] 8 li ve fema le tick s wer e recOl'e red . Of th ese. :3 h ad engo rged a nd dropped, l . lVas thr ee-quart er s eng'urged. th e r e mainin g' U w e re s til l Hat , e \'e n th o ug h th ey had b ee n attach ed th ro ug h o u t th e e ntir e p eriod . It is ass um ed that in sp ring, all would have e ngo rged und er a maxinLlllll of 7' o r 8 da y s. Las t year 's s tudi es ( 1) s u gges ted that th e ca u se o f t hi s ab norm a l feed in g la y pr im aril y in th e ti ck s. Ili st ologica l s tudi es of su c h tick s, after fe edin g t est s, hav e a s yet r e-\'ealed n o u nu s ua l s tru c t u ral differe nce s, beyond advan ce d a nd re tard ed ass imil ative processes . Co mpari so n s of the flat , slow-and fa s t-e ngo rging ti cks, is unfo rtunat e ly imp oss ib le, si n ce at that s t age th e ir feeding potentiali t ies are no t kn o wn, 2) On Janu a r y 18. 1 !J:l7, a se ri es of D. andersoni fema le ti ck s that had bee n coll ec ted during the previo u s spring and had sin ce been k ep t und er a natura l t:iimat e w er e su bj ec t ed to th e fo ll ow in g conditi o n s for a wee k : (a) K e pt at 70° F., humidity 1110 0/0. a nd ir radiated lIith a m e rcury a rc lamp for 10 minntes eac h day , ( di sta nc e fr o m lamp: 1:2 in ch es). ( b ) Kept at 70° F .. humidity 100%. (c) F ln c tnat ed at 1:2 -h o ur int erya ls from n° F. to ,0° 17 .. "a turat ed humidity, Cd ) K e pt at 0° F., humidity 100 % . Th ese t ick s w er e th e n infested in fo ur g r o up s o n a sh eep kept at 1'(lll m t e mperat ur e. ,-\t the e nd o f 5 da ys the g ro up s \\' ere r em o\'e d a nd th e exc ret a of eac h se t coll ec t ed fro m each cage . Proceedings, 1937 9 Th e effec t o f th e va ri o u s trea tme nt s w a s illus trated exce pti o nally \\'e ll by th e cl earl y -de fin ed di ife re n ces of s ize and co lour s had es of th e ti c ks of ea ch g ro up (see a cco mpan y in g ph o t ogra ph ), a nd by th e g raph o j w e igh ts o f ti c k s a nd exc r eta r epr ese n ti ng t h e pro po rti o n s of bl ood ex trac t ed hy ea ch o f th e fo ur gr o up s of ti cks. Th e co rres po ndin g <l \'e rage leng th of t h e ti c k s a nd t he a \'e rage \\' eig ht of ti c ks and exc ret a o f eac h o f th e a bove m e nti o n ed g ro up s \\'e re V.5, S.5 , S.O an d G.5 m Tll .. a nd .H, .J 1, .1 1) an d .OJ g ra m ,.; . T he irra diat ed ti ck s fed n earl y t\\·icc as fa s t as th ose t hat ha d bee n ke p t a t ze r() t elllp e rature. Artificial Feeding Experiments U \v in g tu t h e impr ac ti ca bili ty o f kee pin g a nutri e nt m ediulll s t eril e, a ll expe rim e nt s il1\'o l\' ing th e a rtific ia l feedin g o f t ic k s a r e n ecessa ril y limi ted to a m ax imum of :1O ho urs dura ti o n a t roo m t e mp e rature. S in ce s ig n s of e ngo rge m e nt do n ot beco m e a ppa re n t, exte rn a lly , until sO lll e :2 0 ho urs a fte r a ttac hm e nt. in te rn a l c ha n ges are obser ved to de te rmin e w het h er a ss imil a ti o n o f blood ha s co mm e nced . r\ s lig ht e ngo rge1l1 e nt o f less t ha n 6 ho ur ::; is acco mpan ied by th e dimini s hin g u f ce rta in in t race llul ar pur p le pa rti cles w ithin th e g u t. toge th e r w ith th e a ppea ra nce o f num e ro u s fu c hs in -s t a inin g cy top la s mi c g lo bul es. :3) F ive t ick s w e re in d i\' id ually in v it ed t o fee d by a p rocess des crib ed by Va in s h te in fo r fo r ce d feed in g of l11 usq uit oes (2). T h e ti c k \\'as placed in a g lass t u be, t ape red at th e h ead e nd a nd p lu gged w ith co tto n \ 1'00 1 t o pr eve n t th e animal fr o m bac k in g o ut . Th e ca pillary s t ern o f a s mall funn e l was in se rted thro ugh th e tap ere cl e nd and placed U\'er th e hypos t o rn e o f t he ti ck , th e pa lp s b e ing pu s h ed back a s during no rm a l feedin g . l Iae m o ly sed d e fibrinat ed s h eep's bl ood w a s pl aced in th e ca pillary funn el a nd th e t ick kep t a t roo m t emp e ra ture fo r 30 ho urs. O f (h e 5 ti c ks so tr eat ed, ] \Vas fo und , by se cti o nin g . t o ha\'c t ak e n in blood a nd had co mm e nced to engorge. ,I·) F o ur pa irs of fe male D. andersoni ti ck s w er e tak en fr o m la burato ry s t oc k o n J a nu a ry ] 7, 1037 and place d o n m o u se skin s s tre tch ed uve r th e e nd s of v ial s cu nta inin g de fibrin a t ed hae l11 01y se d s h eep 's blood . After 30 ho urs, half of th ese ti c ks ha d attac h ed . M ic rosc opi c exa min at io n s how ed th a t o nly o n e had co mm e nced t o e ngo rg e. T o t ze (3) . in hi s acco un t o n th e a rtifi cia l fee din g of ti c ks (Ixodes ricinus), s ta t es th a t h e co ul d indu ce th e ny mph s and a dult s t o feed by s ll ch m ean s o nly af te r r e m O\' a l of t he tip s of th e fir s t pa ir of legs . in w hi c h t he o lfa ct o ry o rgan is s itua ted . In Vivo Experiments i5 ) A doze n fe m a le D. andersoni ti c ks were en cised aro und th e p os te ri o r m a rg ll1 o f th e integum e nt a nd p lace d in m edium s o f cl e-10 B. C. E ntolnological Sociely lih rinat ed ha em o lysed s hee p o r ,u in e;l p ig bl ood. E:-; alliin ed aft er 111ten 'a ls o f li to 18 h o ur s. several u f th ese t ick s showe d indi cati ons of e ngo rge m ent. :\ ss illlil a ti o n \I·a s. IWII'e l'e r, not ed o nly in in s ta nces II' he r e the g ut ha d b ee n ru pt ur ed. p e rmi tt in g' the a Cl'ess o f b lolld , In in s ta n ces II' here th e ;..:'ut ha d n u t hee n cut. (l r in uther e:-;perilllents II' he r e attempt s to inj ect bl ood int o t he g ut IHo l'e d un s u ccess ful. it II'a s [ll ul HI that th e surro undin g Huid hac! failed to bring ;d lO u t as;::i milat il'e c hanges. In Vitro Experiments 0) Sel'era l atte mp ts hal'e bee n mad e to cultur e frag m ent s oi li l'ine: tic k g ut in a m ed ium o f s teril e d e llb rinat ed ha e m o ly sed b loo d. Tn no cases, II'h e r e th e g ut ha s bee n r e m oved fr o m th e tick , ha s th e write r bee n ab le t o o btain th e c haract eri s ti c a ss il11ilatil'e chan ges . Acknowledgement