PEOTOPLASTA— THE LOBOSE PEOTOPLASTS. 27 



adherence of the material to a viscid substance, and a gradual entangle- 

 ment and sinking of the food into the body, but through an active exten- 

 sion or flowing of the ectosarc over it, with or without the aid of the pseudo- 

 pods. In the naked forms, the inception may occur in any position of the 

 exterior surface of the body, but, according to the researches of Prof. 

 Duncan,* would appear ordinarily to take place at the posterior extremity, 

 where the endosarc is nearest to or actually reaches the surface. Some of 

 my latest observations apparently confirm this view. 



Whatever may be the position of ingestion in the naked Lobosa, excreta 

 are ordinarily discharged at the posterior extremity of the body adjacent 

 to the position of the contractile vesicle Although there is no true vent, 

 like the positions of the contractile vesicle and nucleus, the position of dis- 

 charge of excrement maintains a certain degree of constancy. 



In the shell-covered Lobosa, the food and water are ingested at the 

 mouth of the shell, usually through the agency of the pseudopods, and the 

 egesta are discharged in the same position at the base of the pseudopods, 

 if these happen to be protruded. 



Many of the Lobosa exhibit, among the constituents of the endosarc, 

 variable proportions of clear, colorless or yellowish oil-globules, and also 

 starch-granules. The latter are no doubt often swallowed as part of the 

 food; but in many cases they appear as if they were an intrinsic element 

 of the endosarc. 



Most of the naked Lobosa frequently contain in the endqsarc more or 

 .less angular particles of quartz sand ; sometimes a few grains, sometimes 

 in large and truly astonishing quantities. The shell-covered Lobosa usually 

 do not contain this material, at least in any obvious quantity. 



Another frequent constituent of the endosarc, especially in some of 

 the Amoebse, consists of minute crystals, often quite distinct, though it is not 

 easy to make out their exact form and constitution. They sometimes 

 appear as octahedrons, rhombohedrons, and hexagonal tables. Auerbachf 

 supposes them to be of a fatty nature ; Carter J describes them as octahe- 

 drons, or modifications of the same, and as probably consisting of oxalate 

 of lime ; and Wallich § speaks of them as rhombohedrons, probably of car- 



* Popular Science Review, 1877, 217. 



+ Zeitsohrift f. wis. Zoologie, 1856, 309. 



t Annals and Magazine of Natural History, 1863, xii, 33. 



J Ibidem, 1863, xi, 434 ; xii, 135. 



