audits Reproductive Cells, 31 



proceeded upon a certain nomenclature of their parts generally ; 

 and I shall pursue the same course here in the description of 

 A. princeps specially. 



The minimum and maximum size of A. princeps may be set 

 down, according to my observations, at ^rjo^h and g- jth of an 

 inch in length, respectively, the breadth bemg a little less. Of 

 course, these measurements may be exceeded either way ; but I 

 have not met with any larger or smaller specimens in which the 

 distinguishing character of the nucleus, which will be presently 

 mentioned, could be detected. 



The most conspicuous features of A. princeps (PI. III.), when 

 it is large, are its size and the number of granules it contains, 

 in both of which characters it much exceeds any other Amoeba 

 with which I am acquainted. Its form, of course subject to 

 protean changes, is for the most part limaceous, or once or 

 twice branched, and its pseudopodia, which are almost always 

 lobed and obtuse, proceed from a posterior end which is 

 normally capped with a tuft of villous prolongations; while 

 the distinguishing character of the nucleus, to which I have 

 above alluded, consists in the nucleolus (fig. Sc?) being so 

 much extended over the inner surface of the nuclear cell that it 

 passes beyond the equatorial line of the latter, and thus causes 

 the pellucid halo which is seen round the nucleus of other 

 Amoeba to be absent ; that is, the nucleolus, being circular 

 and of much less extent than the hemisphere of the nuclear 

 capsule, in most Amoeba, causes it to appear in them as if sur- 

 rounded by a transparent area — which, for the reason above 

 stated, is not the case in A. princeps at the time when it has 

 attained the ;^j-^th part of an inch in length. Besides this, the 

 border of the nucleolus in A. princeps at the same period is 

 wavy ; and this gives rise to an irregular transparent area in the 

 nucleus or nuclear cell. Whether the nucleolus of A. princeps 

 presents the appearance of that in other Amoeba before this pe- 

 riod is a matter of little consequence, inasmuch as, below the 

 minimum size mentioned, all Amoeba appear to be alike. 



Ehrenberg's* and Dujardin'sf figures oi A. princeps are good 

 representations of it. 



Having thus briefly premised a specific description oi A. prin- 

 ceps, let us now give our attention, severally, to the parts of 

 which it is composed, under the following heads, viz. : — Pel- 

 licula, Diaphane, Sarcode, Molecula, Granules, Digestive spaces, 

 Fat-globules, Vesicula, Nucleus, Reproductive cells, and Spermato- 

 zoids. 



Pellicula. — Inference leads us to the conclusion that there' is 



* Infusionsthierchen, Atlas, fol., tab. viii. fig. 10 (1838). 

 t Hist. Nat. des Zoophytes, Atlas, pi. 1. fig. 11. 



