132 CHEMISTRY OF THE ANIMAL PARASITES 



for twenty minutes, and is somewhat impaired at 55-57 for 

 two hours. It is probable that the pathogenic protozoa, at 

 least in some instances, have a semipermeable membrane about 

 them, for Goebel l found that trypanosomes are very susceptible 

 to changes in osmotic conditions. 



CESTODES 



Tsenia echinococcus has been by far the most studied, its 

 abundant fluid content furnishing suitable material for investi- 

 gation. That this fluid is toxic has been repeatedly observed 

 when, through rupture or puncture, the fluid has escaped into 

 the body cavities ; such accidents are often followed by violent 

 intoxication, sometimes by death. 2 The most constant symp- 

 toms are local irritation and inflammation, accompanied by 

 urticaria, which may also be produced experimentally in man if 

 the cyst contents are injected subcutaneously. The fluid is also 

 highly toxic to many animals. As long as the cyst is unopened 

 no toxic manifestations are observed, presumably because the 

 toxic substances do not diffuse through the cyst wall. The 

 nature of the toxic substances is not known, although Brieger 

 isolated a platinum salt of a substance that killed mice. 



The fluid of the echinococcus cysts has generally a specific 

 gravity of 1005-1015, and contains 1.4-2 per cent, of solids. 

 Most abundant are sodium chloride, about 0.8 per cent., and 

 sugar, 0.25 per cent., the latter presumably coming from the 

 glycogen contained in the wall. Cholesterin is often abundant, 

 while inosite, creatin, and succinic acid are often found. Clerc 

 has found traces of lipase, but other enzymes seem to be absent 

 or in very small amounts. Proteids are present only in traces, 

 unless inflammation has occurred. Schilling 3 found the molec- 

 ular concentration of the cyst fluid to be quite the same as 

 that of the patient's blood. 



The cyst wall consists of a hyaline substance which seems to 

 stand between the chitin and the proteids, and probably con- 

 sists of a mixture of both. Because of the chitin it yields 

 about 50 per cent, of a reducing, sugar-like body when boiled 

 with acids. Glycogen is also usually present, but it is limited 

 to the germinating membrane. 4 



Other cestodes, when in the cystic form, contain fluids which 

 are more or less toxic. Thus Moursou and Schlagdenhauffen 5 



1 Ann. Soc. Med. d. le Gand. 1906 (86), 11. 



2 See Achard, Arch. g&i. de'Med., 1887 (22), 410 and 572. 

 3 Cent. inn. Med., 1904 (25), 833. 



*Brault and Loeper, Jour. Phys. et Path, gen., 1904 (6), 295. 

 5 Compt. Kend. Soc. Biol., 1882 (95), 791. 



