56 



SCIENCE. 



studied the subject, a fair idea of the nature and 

 form of Rhizopods. 



In figure (3) we have a representation of the 

 Amceba 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 Dinamceba 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 (iS), Diftiugia piriformis, our Rhizopod 

 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 Diftiugia, 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. 



CUthrulina 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 cha?tophora, represented at figure 

 (1 2), 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 Amceba, 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 Amceba. 



It is, however, a question with us, if Dr. Leidy 

 has not missed such an opportunity during bis 

 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 (Amceba 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 



