16 OF THE RHIZOPODA IN GENERAL. 



ceedino- from it. They are not put forth equally from any part of the surface, but only from 

 some particular portion ; and this portion, in some of the testaceous forms, is very narrowly 

 restricted. They show no tendency to mutual cohesion ; and the smoothness and sharp 

 definition of tiieir outlines makes it obvious that the surface-layer which they derive from the 

 " ectosarc " possesses considerable consistence. No movement of granules is to be seen along 

 their margins ; but the larger pseudopodia receive prolongations from the general cavity of 

 the body (formed by the vacuolation of the " endosarc"), into which its grantdar liquid contents 

 freely pass when propelled by the contraction of the " ectosarc." The differentiation between 

 the " ectosarc'' and the " endosarc" here reaches its maximum ; the former having almost the 

 solidity of a definite membrane, whilst the particles contained in the latter move so readily 

 upon one another as to show that its consistence is not even that of a viscous liquid. The 

 increased tenacity of the " ectosarc" necessarily opposes the free entrance of alimentary 

 substances through any part of the surface ; and it is pretty certain that in some (at least) of 

 the Amcebina, possibly in all, there is a special oral aperture. — This group contains 

 testaceous as well as naked forms, which are all so closely related as to constitute but one 

 natural order; and for these Rhizopoda the name Lobosa may be suggested, as expressing 

 the lobe-like character of their pseudopodial extensions.* 



11. In i\\Q Foraminifera and their alHes, on the other hand, the characteristic features 

 of the Rhizopod type are (so to speak) exaggerated. The pseudopodial extensions present no 

 approach to definiteness, either in shape, size, or number (Plate II, Plate III, figs. 1, 2, 3). Some- 

 times they appear cylindrical, and sometimes form broad, flat bands ; whilst they are often drawn 

 into threads of such extreme tenuity as to require a high microscopic power for their discern- 

 ment; tliey coalesce with each other so readily and completely, that no part of their substance 

 can be regarded as having more than a viscous consistence; their margins are not defined by 

 continuous lines, but are broken by the granules irregularly disposed along them, so thai they 

 appear as if torn ; and these granules, when the animal is in a state of activity, are in con- 

 tinual movement, passing along the pseudopodia from one extremity to the other, or passing 

 across the connecting threads from one pseudopodium to another, with considerable rapidity. 

 In all these particulars they present, as Professor Schultze has pointed out (xcix, p. 314), a 

 striking analogy to the protoplasmic layer of the interior of certain vegetable cells, such as those 

 of the hairs of Tradescantia, which exhibit the aspect of an irregular network formed by the 

 inosculation of threads that spring from the mass immediately surrounding the nucleus, and 

 very closely resembling that which is formed by the pseudopodial extensions of the body of a 

 Liehcrkiihnia (Plate II), or a Gromia (Plate III, fig. 2). And as it is along this protoplasmic 

 network in the interior of the cells of Tradescantia, that the stream of granules moves which 

 has so long attracted the attention of microscopic observers, there is strong reason to believe 

 that this movement is due in both instances to the same agency — a sort of peristaltic contrac- 



* By MM. Claparede and Laclimann (xxv, p. 43t), the Ammbina and the Actinophryna are 

 united into one Order, to which they give the name Proteina. The relationship of the latter, how- 

 ever, to the Acanthometrina, &c., seems to the author so intimate, whilst their differentiation from the 

 Amcebina appears to him to be so decided, that he cannot hesitate iu the belief that the arrangement 

 he has here proposed is much the more natural. 



