56 
SCIENCE. 
studied the subject, a fair idea of the nature and 
form of Rhizopods. 
In figure (3) we have a representation of the 
Amoeba proteus, the most simple and wonderful of 
Rhizopodic forms — it is, to all appearance, a struc- 
tureless gelatinous mass. As the International 
Review states (we fear somewhat rashly) it is 
without organs ; they are certainly not perma- 
nently visible, and so far the most intelligent re- 
search has not discovered them ; but the Amoeba has 
the power of extemporizing such organs as are 
necessary for its existence, and has the means of 
reproducing its species. In the drawing, the 
pseudopoda, or false feet, are seen extended, and 
the animal is sketched while in the act of captur- 
ing an infusorial, by the act of joining the points 
of two of these pseudopoda. 
In the Dinamoeba mirabilis, figure (19), we find 
an advance made in structure, and a more spe- 
cific form ; the interior may be noticed to be full of 
desmids on which the animal feeds, and its posterior 
is widely expanded, so as to embrace a cord of 
Didymoprium. 
In figure (18), Difflugia pyriformis, our Rbizopod 
is now found with a case or shell formed of irregular 
particles of quartz sand. 
The empty shell of another of the same species, 
D. lobostoma, is shown at figure (14). The shell 
is composed of rectangular and oval plates, with 
dotted intervals. 
Another of the Difflugia, D. Corona, at figure 
(22), still with a case formed of the same material, 
but of a somewhat different form, and having eleven 
spines ; on the reverse side, the mouth would have 
been seen armed with teeth. 
In figures (1) and (7), D. Constricta, we have 
further examples. In the original drawing they are 
colored a light redish-brown, whereas the previous 
examples were colored a blackish tint. 
We now approach a beautiful design in form, 
the Nebela collaris, figure (11), the sarcode being 
contracted in the shape of a ball. 
The design shown in figures (2) and (9), Arcella 
vulgaris, is still more beautiful and decidedly ap- 
proaching the delicate patterns seen on the silicious 
valves of diatoms. The first in the original draw- 
ing is colorless, the second a light-brown, the sar- 
code being encysted. 
In figure (20) is seen the empty shell of Cypho- 
deria ampulla, having a form somewhat similar to 
the Marine Rhizopods ; the spur-like process may 
be noticed. 
Clathrulina elegans, figure (4), is a very beauti- 
ful and remarkable form of Rhizopod, having a 
yellow colored lattice shell, enclosing sarcode in 
two balls, and supported by a stem of the same color. 
In other specimens Dr. Leidy shows the sarcode 
balls emitting numerous rays ; this appears to be 
omitted in the present drawing. 
At figure (6), Diplophrys Archeri, is a form of 
a different class taken from the swamp water on 
the mountains of Pennsylvania. Dr. Leidy de- 
scribes them as composed of multitudes of minute 
globular individuals aggregated in masses, which 
in their movement causes the whole to undergo 
a change of shape. The corpuscle seen in each 
transparent body should be .colored a bright cherry- 
red, to imitate the original drawing. 
Acanthocystis chaetophora, represented at figure 
(12), is very similar in form to the Actinophrys sol, 
or Sun animalcule, of the text books. The body is a 
finely granular protoplasm, invested with numerous 
delicate, silicious rays, implanted by minute basal 
disks ; there are also numerous soft rays, like those 
of the Actinophrys, but distinguished from the sil- 
icious rays by the former ending in a simple pointed 
or furcate extremity. 
We have now carried our readers briefly through 
Dr. Leidy’s book, and have shown the beauty and 
variety of the forms studied. The interest attached 
to such investigations is obvious, and they are 
within the reach of every student. Considerable 
work has still to be done in this direction, and 
however great may be that done by Dr. Leidy, 
we feel sure that he would be the first to admit that 
so far the ground has been but broken. 
To our mind it seems most important to concen- 
trate future work on the genus Amoeba, for therein 
lies the nucleus of the most valuable discoveries, 
which may even be of the highest importance to the 
human race. What is required in this direction is 
the constant and continuous observation of a 
single individual of the species, so as to arrive at its 
life history. We did hope that Dr. Leidy, in his 
present work, would have added to our knowledge 
on this point ; but he frankly admits that neither 
himself nor others profess much knowledge relating 
to the reproduction of the Amoeba. 
It is, however, a question with us, if Dr. Leidy 
has not missed such an opportunity during his 
recent investigations. 
At page 49 of this work on Rhizopods we notice 
Dr. Leidy describes what he calls an act of canni- 
balism, when he saw an individual (Amoeba pro- 
teus) swallow and digest one of another species 
(Amoeba verrucosa). We would ask, was this 
really an ingestive or a sexual act? Dr. Leidy takes 
the former view. With great respect for his 
