78 MOIU'HOLOGICAL DEVELOPMENT. 



ated, if not positively undifferentiated, that animal individu- 

 ality can scarcely be claimed for them. Figs. 131, 132, and 



133, represent certain nearly-allied types of these Amoebi, 

 ActinopJirys, and Lieberkuhnia. The viscid jelly or sarcode, 

 comparable in its physical properties to white of egg, out of 

 which one of these creatures is mainly formed, shoAVS us in 

 various ways, the feebleness with which the component physio- 

 logical units are integrated shows us this by its very slight 

 cohesion, by the extreme indefiniteness and mutability of its 

 form, and by the absence of a limiting membrane. Though 

 unqualified adherents of the cell-doctrine assert that the 

 Amoeba has "an investment, yet since this investment, com- 

 pared by Dujardin to the film which forms on the surface of 

 paste, does not prevent the taking of solid particles into the 

 mass of the body, and does not, in such kindred forms as Fig. 

 133, prevent the pseudopodia from coalescing when they 

 meet, it cannot be anything deserving the name of a cell- 

 wall. A considerable portion of the body, however, in Difflu- 

 cjia, Fig. 134, has a denser coating ; so that the protrusion of 

 the pseudopodia is limited to one part of it. And in the 

 solitary Foraminifera, like Gromia, the sarcode is covered 

 over most of its surface by a delicate calcareous shell, pierced 

 with minute holes, through which the slender pseudopodia 

 are thrust. The Gregarina exhibits an advance in 



integration, and a consequent greater definiteness. Figs. 

 135 and 136, exemplifying this type, show the complete 

 membrane in which the substance of the creature is con- 

 tained. Here there has arisen what may be properly called 

 a cell : under its solitary form this animal is truly unicellular. 

 Its embryology has considerable significance. After passing 

 through a certain quiescent, " encysted " state, its interior 

 breaks up into small portions, which, after their exit, assume 



