DR. WALLICH, ON AM@BA. 195 
needful. The prehensile power of the papille is very great, 
so much so that when undue pressure has been exerted upon 
one of the Amcebe it has been torn asunder, the portion 
provided with the villous area remaining attached to the 
glass slide on which it had been placed for observation. The 
great abundance of the Amcebz in question in the ferrugi- 
nous ponds of Hampstead, more than 95 per cent. of all the 
specimens being furnished with papille, has induced Dr. 
Wallich to consider this as a distinct species, which he pro- 
poses to call Ameba villosa. He, however, admits at the 
same time the probability of all the species of Amcebze being 
local forms of one and the same type. The largest specimen 
which Dr. Wallich observed was =;th of an inch in SEabeses 
The villi, in their quiescent state, seem to be about ;,1,,ths 
of an inch in average length. In some instances the 
villous portion was placed on a long pedicle of ectosarc, so 
as to give it the appearance of a brush. In these specimens 
the villi seemed to have lost their prehensile power. In 
many cases an infundibuliform orifice was observed in 
the centre of the villous patch, from which numerous par- 
ticles of matter were extruded, and also minute, perfectly 
formed Amcebe, which Dr. Wallich regards as a proof of 
viviparous parturition among Amebe. The orifice was only 
temporary, but recurred frequently in the same position in 
various specimens and at various times. Dr. Wallich’s ob- 
servations on the nucleus and contractile vesicle are extremely 
interesting, and of great importance. He says, “‘ The nucleus 
consists of a pale, gray-coloured, spherical mass of granules, 
towards the centre of which may occasionally be detected a 
minute, clear nucleolus. J¢ is contained within a hyaline and 
somewhat elongated vesicular cavity, but never occupies the en- 
tire area of the latter.” This vesicular cavity is separable from 
the rest of the Ameeba, as a clear, membranous capsule, con- 
taining the granules of the nucleus. Dr. Carpenter and Mr. 
Carter have both spoken of the existence of a vesicular boun- 
dary to the nucleus, but they do not allude, Dr. Wallich be- 
lieves, to the highly specialized membranous covering which 
is so remarkably manifest in A. villosa, and which seems to 
approach more nearly to the vesicle of the Gregarinide. Dr. 
Wallich assimilates it to the nucleus of Plagiocantha, Tha- 
lassicola, Acanthometra, and Dictyocha. The position of the 
nucleus in A. villosa is always, when at rest, in the vicinity 
of the villous patch. With regard to the contractile vesicle 
of Amceba, Dr. Wallich is of opinion, from careful obser- 
vation, that it is not formed by any definite wall, as Car- 
penter and Carter have described it. In A. villosa the con- 
