204 SARCOSI'ORIDIA. 



tlic u\> lying in the direction of the long axis. According lt> 

 Fielnegcr. the striated membrane is not ectoplasm, but altered 

 muscular tissue. Some hold that this cuticle is transversed by 

 tine pores, which are very minute, and not of such a size as to 

 give <»ne the idea that a body of the size of the sarcosporidial 

 sickle or spore could pass throtigh them. 



As the ])arasite grows it gradually distends and destroys 

 the muscular t"il)re, in which it is parasitic, until linally it is sur- 

 munded merel\- l)y the sarcolemma and sarcoplasm, and drops 

 out into the connective tissue. This, then, is the way in which 

 the intramuscular parasite { Sarcocystis ) becomes the conneciive 

 tissue ]iarasite { Halhiiina ) . 



.^i'()K]-:s, .Si'(»K()/.()iTi:s, OK l\.\i N i-.n's C(»ri'L'scli-:s. 



\'ery little is known about the life history of the Sarco- 

 sporidia. and the exact structmx" of the spore is still a matter 

 of dis])ute. More(^)ver, it is ])Ossible that there is more than 

 one kind of s]>ore even in the same species of animal. The 

 lengths of tlie s])ores kw.ve l)een given by dilferent investigators 

 from 4-S- 10-13 /<• •"^'' ''1*-' breadth from 1-2-^^-5 u. lUanchard 

 teased out the cysts of the Sarcocystis imiris, and found tliat 

 the sporozoites exhil)it ])eculiar tuovements when observed in a 

 salt solution in a warm stage, and soon change iheir form 

 slightly. Motih't\- of the spores seem to l)e a feature of some 

 s])ecies. The s])ores are very fragile, and can easily l)e dis- 

 sociated by kee])ing them in a moist clianil)er. or l)y treating 

 them with \er\ dilute acids or alkalis. Its rel;iti\e fragility, 

 the action ot water on it, etc., a]ipears to indicate that the s])ore 

 does n(»t I'epresent the form under which the ]>arasite ])reserves 

 itself in the outer world. Negri. i-"iel)iger, \'an []etgh, 'I'eich- 

 man, believe that the so-called spores of the sarcocysts of the 

 moust-. liorse and shee]) re])ro(lnce themselves by fission, and 

 so are not spores in realitx. ."^ome l)elieve that several I<inds 

 of s])ores have different functions. Apparently the more coni- 

 ])licated spore is ])ropagative in function, serving to infect new 

 hosts, wliile the simi)le form, which should perha])s be regarded 

 as a sjioroblast. as a sini]ile cell not differentiated as a s|)ore, 

 serves for sjjreading the infection in the same host. ^fhe 

 occurrence of the sim])le type of spore in the sarcocyst of the 

 mouse wdidd account for the manner in which the parasite over- 

 runs its host and is usttally lethal to it, while the sarcocyst of 

 the sheep, whicli ai)])ears to produce chietiy propagative spores, 

 is a harmless i)arasite. According to Laveran and Mesnil, the 

 sporozoites of the sarcocysts found in sheep are sausage-shaped, 

 cm-ved, with one end more ])ointed than the other. At the 

 l^ointed end is a striated structure representing a polar capsule, 

 and at the l)luiit end is a nucleus, while the middle of the body 

 is occui)ied by coarse, dee])ly-stained metachromatic grains. With 

 reference to the |)olar cai)sule, about which there is a diversity 

 of opinion, Minchin divides the Neosjioridia into two sections, 

 kncjwn res])ectivel\- as the Cnidosporidia and the Hajilosporidia. 



