190 BIOLOGY OF THE PROTOZOA 



granules. If the neutral red staining granules about the gastric 

 vacuoles are bearers of ferments as maintained by Prowazek, they 

 certainly are secretory in nature. There is some uncertainty, 

 however, as to the identity of these with the so-called excretory 

 granules. The more recent experiments of Slonimski and Zweibaum 

 (1922) show that there are two types of these granules which they 

 call A and B, and that the peripheral granules (B) which exude from 

 the membrane vary in ninnber and size according to external con- 

 ditions of temperature and internal conditions of vitality, being 

 rare or absent prior to conjugation. The nature of these varying 

 granules and their function in metabolism are unsolved problems 

 at the present time. 



In connection with secretions we may take into consideration 

 the various poisons produced by Protozoa either in the form of 

 toxins exuded by the individuals and soluble in the surrounding 

 medium, or in the form of endotoxins which are liberated only 

 when the individual is disintegrated. What little is known about 

 these secretions is mainly in connection with parasitic forms and 

 here knowledge is limited to the effects produced upon the host. 

 In general it may be stated that, if we except the toxins produced 

 by the so-called Chlamydozoa (particularly smallpox and rabies 

 organisms), the poisons of protozoan origin are much slower and 

 indefinite in their action on the host than are bacterial toxins, and 

 the course of the specific diseases caused by pathogenic protozoa is 

 relatively much slower than diseases caused by bacteria. Rela- 

 tively few toxins of protozoan origin have been extracted and used 

 in experimentation. One such, called sarcocystin, was obtained 

 from sarcosporidia by Pfeiffer and Gasparck and by Laveran and 

 Mesnil (1899). The latter found that rabbits are soon killed by 

 the blood injection of sarcocystin in glycerin solution, also that 

 crushed cysts give rise to characteristic pathological effects in the 

 muscles, whereas no such reaction accompanies the presence of 

 uninjured cysts. 



Filtered blood of malaria victims, if taken at the height of parox- 

 ysm and injected into a malaria-free individual, produces in the 

 individual a characteristic malarial paroxysm according to Rosenau 

 and his co-workers, and analogous "paroxysm toxins" have been 

 detected in connection with other l)lood parasites. Such experi- 

 ments indicate that toxins from malaria organisms produce rather 

 intensive effects of a generalized character. 



Toxins from organisms of amoebic dysentery are more regional 

 in their action, causing local ulceration and abscess formation indi- 

 cating a cytolytic process possiblx' due to secretions of digestive 

 fluids. There is still some uncertainty, however, in regard to this 

 matter, and the possibility of participation by bacteria in the 

 reactions is not excluded. 



