578 



SARCOSPORIDIA 



as male and female moths. Since the sexual organs are infected with 

 the parasites they transfer the infection to the ova and from these 

 to the young caterpillars. In this manner the infection may be con- 

 tinued from generation to generation, bringing about both great 

 mortality and an inferior quality of cocoons. Pasteur showed how 

 to distinguish microscopically the infected from the non-infected 

 ova, and in this manner enabled the breeders of silkworms to weed 

 out the disease. 



FIG. 202 



Nosema bombycis: 1 to 5, spore formation; 6, infected follicle of testicle; 7, spores; a, b, 

 fresh; c, d, treated with nitric acid. The acid causes them to swell up and increase in size by 

 at least a half, at the same time making the polar capsule distinct. In d, the filament is 

 extruded. (After Balbiani.) 



SARCOSPORIDIA. 



Sarcosporidia are protozoan parasites occurring in the muscle 

 fibers of a large variety of animals, such as hogs, sheep, cattle, horses, 

 dogs, cats, rabbits, rats, mice, monkeys, chickens, and some other 

 domestic and wild birds. They have also been occasionally found in 

 the muscles of man. In the muscles of affected animals sarcosporidia 

 form elongated sausage-like spore sacs, which have been known for 

 a long time as Miescher's or Rainey's tubules. These spore sacs 

 generally measure from ^ to 4 mm. in length, but there is a sarco- 

 sporidium (Balbiana gigantea) found in the esophagus of sheep 

 which may attain the size of a hazelnut. Older spore sacs sometimes 

 show a double membrane, the outer one exhibiting a radial striation, 

 as if it were provided with short, rod-like cilia. The real character 

 of this structure has not yet been clearly made out; it is now more 

 generally believed that the striae represent fine pore-canaliculi. The 

 interior of the sac is divided into compartments by fine partition 

 walls arising from the inner membrane. Included in these chambers 

 are the sporoblasts and their spores. In the entoplasm of the smallest 

 sacs, balls 4 to 5 micra in diameter, which show an indistinct nucleus, 



