CKHTOliEK l^*^ 



mune while some acquire innnunity through previous nifection.- 

 The blood of persons with malaria seems to contain no antibodies tor 

 the parasite (Ferrannini)r^ although it seems to have some antihemo- 

 lytic power (Brem). (Concerning the pigment present m the ma- 

 larial parasites see "Pigmentation," Chap, xvi.) , , ,, ^ 

 Sarcosporidia of sheep yield aqueous and glycerol extracts that 

 are hiohlv toxic for rabbits (Pfeiffer), the poisonous constituent of 

 which %as called sarcocusiin by Laveran and ^lesnil.- Tins is so 

 highlv toxic that 0.0001 gm. is fatal to rabbits (per kilo), other ani- 

 mals "being less susceptible. It loses its toxicity on heating at 80 

 for twentv minutes, and is impaired at 55-57° for two hours It 

 produces pruritis and other anaphylactic symptoms, and although the 

 serum of sheep with this parasite does not confer passive anaphylaxis 

 to sarcosporidia, vet it does give positive complement fixation.-- Ihat 

 it is a true toxin is shou^n by Teichmann and Braun,-^ who produced 

 an effective antitoxin by immunizing rabbits; only rabbits seem to 

 be susceptible to the toxin. The sarcosporidia contain also a distinct 

 theinnostable agglutinin. The lethal dose of dried substance of sar- 

 cosporidia is. for rabbits, but 0.0002 gm., and the poison seems to 

 unite with the lipoids of the nervous system (Teichmann).- it is 

 probable that the pathogenic protozoa, at least in some instances 

 have a semipermeable membrane about them, for Goebel -^ found that 

 trypanosomes are very susceptible to changes in osmotic conditions. 



CESTODES 

 T^nia echinococcus has been by far the most studied, its abundant 

 fluid content furnishing suitable material for investigation. That 

 this fluid is toxic has been repeatedly observed when, through rup- 

 ture or puncture, the fluid has escaped into the body cavities; such 

 accidents are aften followed by violent intoxication, sometimes by 

 death =" As long as the cvst is unopened no toxic manifestations are 

 observed The most constant symptoms are local irritation and in- 

 flammation, accompanied by urticaria, which may also be produced 

 experimentally in man if the cyst contents are injected subcutane- 



""""The svmptoms are so strikingly similar to those of anaphylactic 

 intoxication, that it is now generally believed that they are the result 

 of such a reaction in a pei^son sensitized by absorption of antigenic 

 substances from the cyst." Carriers of echinococcus cysts have been 



20 See Celli. Cent. f. Bakt.. 1900 (27). 107. 



2iRiformaMed.. 1911 (27), 177. 



22Compt. Rend. Soc. Biol.. 1800 (51). .311. 



22a McGowan. .Tour. Path, and Bact., 1913 (18), \lo. 



24 7b7rf ' l01o7''0)*'."96: see also Knebel. Cent. f. Bakt., 1912 (66), 52.3. 

 25Ann.*Soe. Med. d. le Gand. 1900 (86). 11. 

 26Rpp 4ehard \rch "en. de Med.. 1887 (22), 410 and 5(2. 



27!:: BoS^in and Lar'-oche. Presse Med., 1910 (18), 329; Ghedini and Zamorani, 

 Cent. f. Bakt., 1910 (55), 49. 



