184 RHIZOPODA. 



These chambers in some species lose their continuity, and, retain- 

 ing their contents, lead an isolated life ; and this may be the more 

 readily regarded as a form of asexual reproduction, since the single- 

 chambered fresh-water Rhizopoda also not unfrequently protrude 

 their contents to a greater or less extent out of the chamber, and by 

 the secretion of a shell form a new organism. 



Simple division (which, however, when the portions are of unequal 

 size, looks more like budding) is apparently very common among the 

 Rhizopoda. But we further find a second kind of reproduction, in 

 which the body-mass, like the yolk of a fertilised ovum, falls into a 

 varying number of pieces, each of which then becomes a distinct 

 organism, and often finds its way to the exterior in the temporary 

 form of a swarm-spore, provided with a single cilium. As an ante- 

 cedent to this process, the naked so-called Amoebae first surround 

 themselves with a membranous covering, which encloses the body 

 like a capsule ; but this may be also secreted under other circum- 

 stances, e.g., in the scarcity of water. Protected by this capsule, the 

 creatures can undergo desiccation without danger, just as do the eggs 

 of the Nematodes, previously mentioned (p. 53). 



In those Foraminifera which have tests, the fonnation of the 

 brood takes place in the several chambers, inside which the young 

 are, in many species, surrounded by a shell, so that on the rupture of 

 the enclosing test they issue forth resembling their parents. 



The swarm-spores of Radiolarians arise in the central capsule 

 that is, in the nucleated central substance. 



It was demonstrated as early as 1859, by Lainbl, that the Rhizo- 

 poda included forms parasitic in man. 1 In the intestinal mucus of a 

 child who died of enteritis, there were observed not only small naked 

 amoeboid organisms, 0'004 to 0'006 mm. in diameter, but also shell- 

 bearing Diffluyiw and Arcellcc (O'Ol to O'OIG mm.), which are found 

 normally only in ponds and ditches. The representation which Lambl 

 gives of these creatures is, however, so incomplete, that their identifi- 

 cation seems in the highest degree suspicious. At any rate, such a 

 discovery, so long as it remains uncorroborated, can hardly be regarded 

 as established. But since we know from other quarters of the occur- 

 rence of a parasitic Amoeba in man, it is a reasonable supposition that 

 at least some of the observed bodies were indeed nothing else than 

 parasitic Rhizopoda. 2 Amcebce are also to be observed as parasitic in 

 various conditions in other higher and lower animals ; 3 but only 



1 " Aus dem Franz- Joseph-Kinder-Spitale," Bd. i., p. 363, Taf. xviii. 

 a Apart from the loose or otherwise altered epithelial cells, others might be referred 

 to the group of Monads. 



3 Thus, for example, Lieberklihn reports the occurrence of A mocha in the intestine of 



