3 o6 THE SPOROZOA 



p. 89). The allegation stands therefore in need of further 

 support; the most recent investigators, Laveran and Mesnil [119], 

 were unable to bring about extrusion of a filament from the 

 spore. But although complete identity of structure has not been 

 established, it is nevertheless extremely probable that the spirally 

 striated body of the Sarcosporidian chlamydospore 

 is strictly homologous (i'.e. homogenetic) with the 

 Myxosporidian polar capsule, and is an additional 

 proof of the relationship between the two groups. 

 The gymnospores, commonly described under 

 the names of " sporozoites " or "Rainey's cor- 

 puscles," vary a good deal in size and appearance 

 (Figs. 120, 121, 123). Their form has been com- 

 pared in different instances to that of a bean, 

 FIG 123 kidney, crescent, sickle, or banana. In Sarcocyslis 



Gymnospores of muris they are about 1 2 p by 4 //, in dimensions, 

 urfSe p'igThow" ^ut * n otner species they may be larger than this, 

 ing their changes of or much smaller (3 or 4 p. x 1 fj.). Each consists 

 " of finely -granulated protoplasm, containing a 

 nucleus, a few coarser granules, and sometimes 

 one or two vacuoles. Those of Sarcocystis muris show active 

 movements when warmed up to 35-37 C. They perform gliding 

 movements on a circumference corresponding to their own curva- 

 ture, occasionally revolving also on their long axis, and thus 

 producing "a boring or screw-like action" (Smith). In other 

 cases they are said to become amoeboid under similar conditions. 

 Both kinds of movement are probably to enable them to penetrate 

 the tissues of the host. 1 



With regard to the significance of the two kinds of germs, and their 

 destiny and further development, very little can be asserted definitely at 

 present. The whole question of the reproductive bodies of the Sarco- 

 sporidia is,, indeed, in a very confused state, and to generalise with regard 

 to them is difficult, since no single observer seems to find more than one 

 kind of spore. Those who, like Laveran and Mesnil, describe spores, say 

 nothing about any gymnospores ; and those who, like Smith and Koch, 

 describe gymnospores, do not appear to be aware of the existence of any 

 other kind of spore. It might be inferred from this that some species, 

 such as Sarcocystis tenella, produce only chlamydospores, and others, such 

 as S. muris, only gymnospores, but it is far more likely that both kinds 

 are produced by the same parasite, sometimes the one, sometimes the 

 other occurring, as the result of conditions as yet unknown. It is note- 

 worthy in this connection, that S. muris, in which only gymnospores have 



1 Besides the two kinds of germs described above, cysts have been described con- 

 taining spermatozoon -like structures (see Wasielewski [7], p. 125), but from the 

 accounts given it is difficult to form any clear idea of the nature of these bodies, 

 or of their significance in the economy of the parasite. 



