GENERAL PHYSIOLOGY 197 



by him and by Nirenstein (1905) to pass into the gastric vacuole 

 and to mix with the food substances from which circumstance they 

 were regarded by both observers as the bearers of ferments (trypsin- 

 like according to Nirenstein). The so-called Excretperlen (excre- 

 tory granules) first described by Prowazek (1897) and interpreted 

 by him, by Nirenstein and by Doflein (1916) as furnishing evidence 

 of excretion through the general cell membrane, with equal justifi- 

 cation may be interpreted as secretory 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 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 number and 

 size according to external conditions of temperature and internal 

 conditions of vitality, being rare or absent prior to conjugation. 

 The nature of these varying granules and their function in metab- 

 olism are still unsolved problems. 



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 (see 

 Chapter X). In general it may be stated that, if we except the 

 toxins produced by the so-called Chlamydozoa (particularly small- 

 pox 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. 

 Relatively 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 blood parasites. 



Toxins from organisms of amebic dysentery are more regional 

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



