434 Dr. G. C. Wallich on Amoeba villosa 



XLVII. — Further Observations on Amoeba villosa and other 

 indigenous Rhizopods. By G. C. Wallich, M.D., F.L.S., 

 F.G.S., &c. 



[Continued from p. 371 .] 



[Plate X.] 

 Before proceeding to offer a few general remarks on the rela- 

 tions of Amoeba villosa, and two other forms obtained from the 

 same locality, with the rest of the group to which they belong, 

 it is desirable that I should adduce some supplementary ob- 

 servations made by me during another month's study of these 

 organisms. 



In many specimens of the Amoeba, and more especially such as 

 appear to be in full vigour of growth, the protoplasm is densely 

 charged with certain granules, of larger size than those mere 

 points which pervade it under all circumstances, but nevertheless 

 extremely small. If examined cursorily, these granules may rea- 

 dily be mistaken either for extraneous bodies derived from with- 

 out, or for mere consolidated particles of the sarcode itself. They 

 are so minute as to render it difficult to trace any difference in 

 their dimensions, when seen under the medium powers of the 

 microscope. But their aspect when isolated along with a thin film 

 of their sustaining protoplasm, and examined under a power of 

 from four to five hundred diameters, at once led me to suspect 

 their crystalloid character ; and this view was fully borne out on 

 submitting them to a still higher degree of magnifying power ; 

 for whilst no analogous bodies, or, indeed, any insoluble saline 

 particles, were discoverable in the material in which the Amoeba 

 were contained, these crystalloids proved to be distinct rhombo- 

 hedrons possessing a higher index of refraction than water. They 

 measure in length from yj^ooth to ^jg^th of an inch, with a 

 breadth of from ^ u o"o o"^ to j uVo^h °* an inch. Their minute- 

 ness renders the precise definition of their angles a matter of con- 

 siderable difficulty ; but nevertheless, by taking the mean of a 

 number of measurements, I found the more obtuse angle to be 

 about 140°. Hitherto I have been unable to determine their na- 

 ture by chemical tests, further than discovering that when a slide, 

 on which a number of the Amoeba have been dried, is treated 

 with dilute hydrochloric acid, all trace of the crystals is entirely 

 lost. Coupling their rhombohedral figure with this fact, it seems 

 probable that they may consist of carbonate or some other salt 

 of lime. This, however, is a point demanding further careful in- 

 vestigation. I may mention that precisely similar crystalloids 

 have also been detected by me in the sarcode of Euglypha, Ar- 

 cella, and Acanthometra. (See PI. X. fig. 7.)* 



* As is well known, " prismatic crystals " were observed by Huxley in 

 Thalassicolla. 



