FLAGELLATE INFUSORIA AND ALLIED ORGANISMS. 101 



Stretched far forwards from the pointed extremity of the 

 body ; the pseudopodia, however, are not retracted. 



In this condition the nucleus is situated in the pointed 

 anterior extremity from which spring the ilagella. It is 

 remarkable that after moving, at most for a short time, by 

 means of its flagellum, the little organism returns to its 

 creeping mode of life.^ 



Amceba Blattae, n. sp. von Siebold.- The author has 

 already^ given an account of the peculiar appearances observed 

 in the nuclei of Amoeba princeps, showing that the number 

 and size of the nuclei undergo great variations. The same 

 changes have lately been found to occur in other Amoeba. 



The Amoeba hlatta (PI. vi, fig. 26) rivals in size the 

 Amceba pri7iceps ,\i is found as a parasitein the dilatation at the 

 commencement of the rectum in the cockroach. I^ this situa- 

 tion it lives with Oxyurus, Nyctotherus oralis, Lophomotias, 

 and numberless small Flagellata. On making a preparation to 

 show the living entoparasitic Amoebae contained in this posi- 

 tion, they may be seen as round, and apparently lifeless 

 masses, which soon exhibit their somewhat sluggish move- 

 ments, thereby declaring their true nature. The proto- 

 plasm of this species appears to be neither homogeneous, 

 alveolar, nor reticular, as in many other Protozoa, but 

 always very markedly fibrillar. On close investigation 

 it may be noticed that it appears to be made up of 

 numerous dark threads, which are somewhat irregular, and 

 are occasionally knotted or granular. These threads either 

 run more or less regularly in reference to the direction of 

 movement of the body, or they cross it somewhat confusedly. 

 A clear intermediate mass separates individual threads from 

 each other : from its refractive index, and its feeble reddish- 

 colour, this mass appears to be fluid. A peculiar homoge- 

 neous outer layer, the ectoplasm, such as is often found in 

 Amoebge, and amoeboid organisms, is not here normally 

 present. The contour of the body is formed by a layer of 

 dense protoplasm, which is usually very delicate ; from this 

 layer arise the protoplasmic threads of the body, and with it 

 they are in direct continuity. This dense surface layer of 

 protoplasm is often heaped up at certain spots in the body 

 into great masses (fig. 26 a), in which case it is seen as 



1 " On Free-swimmins: AincEbse," see also Cienkowski, ' Pringsh. Jhrb. f. 

 w.,' Bd. iii, p. 434, and Tatem, ' Month. Micr. Joiirn.,' i, p. 352. 



*Beitia<;e ziir kenntniss Wirbelioser Tbiere,' Danzijj, 1839, p. fi9. 

 3 'Studien iibcr die ersten Enlwickelungs^ organge,' etc., p. 1()4. 



