CHAPTER XIV 



VENOMOUS ANIMALS: PROTOZOA TO 

 ARTHROPODA 



Protozoa — Coelenterata — Echinodermata — Platyhelmia — Nemathelminthes — 

 Arthropoda — Arachnida — Scorpionidea — Aranea — ^Acarina — Chilopoda 

 — ^Hexapoda — Anopleura — Hemiptera — Hymenoptera — Lepidoptera 

 — Dip tera — Coleop tera — MoUu sea — References . 



VENOMOUS ANIMALS. 



Many species belonging to the various classes and orders of the 

 animal kingdom possess glands which secrete chemical substances 

 injurious to man and the higher animals. The exact nature of 

 these chemical substances is but little understood at present, 

 though of late years much advance has been made in the knowledge 

 of their action, which seems to be of a nature similar to that of 

 bacterial toxins. 



It will be best to consider these venomous animals i the order 

 of their zoological classification. 



PROTOZOA. 



Rosenau and his collaborators have succeeded in produc- 

 ing a malarial paroxysm in a healthy man by injecting blood- 

 serum taken from a malarial patient during the cold stage of the 

 fever, and previously filtered through a Pasteur-Chamberland 

 filter. Casagrandi and De Blasi have also described a haemo- 

 lytic toxin, concerning which more will be said when malaria 

 is discussed. 



Laveran and Mesnil have shown that Sarcocystis tenella produces 

 a toxin, sarcocystin, of which o-i milligramme will kill i kilogramme 

 of rabbit with choleraic symptoms, while a less dose will produce 

 fatal cachexia. It is, however, less toxic to other animals. 



CGELENTERATA. 



The Coelenterata include anemones, corals, and jelly-fishes, which 

 are capable of stinging by means of certain special cells called cnido- 

 blasts, which enclose nematocysts— little sacs — the invaginated 

 neck of which is continued into a long, hollow, spirally coiled fila- 

 ment, surrounded with poisonous fluid. When stimulated, these 



203 



