VARMF.RS' IXSTITI'TKS. 807 



iiiu tiuailfis should n«>i he .illowcd to bt'i-onir dusty. Medicine is of little 

 vnhie in this disensi-. A tiuuijiatiou of tar or turpentine may be tried 

 if desired. More can i»e acconiplisheil by feediiiir a lii«hly nutritious 

 ration, and waiting' until a.sje will irive the n»'cessary strenjrtli and lesist- 

 ance to overcome tlie disease. 



Parasitic Diseases ot the l,iver— Kchinocot'cus Hydatids.— The disease 

 caused hy tin- larval sta.ue of the taenia Echinococcus is known as hydatid 

 or Echinococcus disease. Doiis and wolves a<-t as hosts for the mat»ir»' 

 form of tliis tapewornt. and the immature form is found in domestic ani- 

 mals. It is commonly found in lioiis and cattle and is frequently seen 

 in the liver. luni;s. etc.. of animals killed in tlie abattoir. .Man may also 

 a<-r as host for the larval form. 



l>esciiption.-The larval form appears in the form of cysts, jrenerally 

 ni the liver, hut they may )»e found in the lungs, heart antl various other 

 orjrans of the body. After four weeks from the time <»f becominir 

 infected liy the embryo, small cysts about one tweiity-tifth of an inch 

 in diameter may lie noticed in the infected orjxans. The outer wall of 

 the cyst is formed by the connective tissue of the organ in which it is 

 located. AMthin this is the young parasite. Its outer i>art or capsule 

 is rather tiaiisjcircnt. the inside granular and somewhat condensed on 

 the periphery and (•(•utaining cells which are distinctly sei)aiated from 

 one another. The cyst grows slowly, and at the end of eight weeks 

 has about doubled in size. The elastic cuticle is then much tliicker and 

 its inner surfac*- is covered by a thin membrane, tlie germinal layer, 

 which represents the condensed granular contents. In tlie center of the 

 cyst is a cavity containing a clear watery fluid. As the hydatid grows, 

 the cuticle be<:omes stratitieil and the germinal layer becomes differenti- 

 ated int<» small cells (H'cui>ying the periphery, large cells «m the inside 

 and granular cells occupying (he irregular spa<es on the surface. At the 

 end of nineteen Aveeks the i>arasite is aVmut two-fifths of an inch in 

 diameter. I*rotulierances gradually grow into the cavity and develop into 

 broad cai>sules. and it is in these capsules that tlie head of the succeeding 

 generation of tapeworm develops. Numenms broods of capsules may 

 form in one cyst and many thousand heads may lie ]>resent in one hydatid. 

 Several modes of growth are open for the parasite. Centei-a of growth 

 may form in the wall of tlie hydatid: these are called daughter cysts. In 

 turn a third generation may form in the same maniu'r in the daughter 

 cyst; these are called granddaughter cysts. .\s they develop, they will 

 burst through that iiart of the hydatid wall offering the least resistance, 

 sometimes on the inside of the wall and sometimes on tlie outsid«' «)f it. 

 Tor this reasiui they are called endogenous and exogenous cysts. When 

 a jji-oup of small hydati«ls lie close together and are connected by a com- 

 mon stroma, they are called Ediinococcus mulliUMularis. Sometimes as 

 a result of the formation of daughter and granddaughter cysts, they take 

 nil the form of :i bniicii of grapes; they are then named E. racemosus 



