ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
51 
as a ladder along whicli they creep ; the protoplasm advances on both 
sides of the prey, till at last it completely incloses it in its middle. 
In both cases the author observed what he calls a halo round the prey ; 
in the former it is the surrounding liquid, imprisoned with the prey 
between the walls of the vacuole ; in the latter it is, partly at any rate, 
due to a secretion of the animal. When the prey is about as large as 
Actinophrys itself there is no halo, and the mode of prehension is some- 
what different. 
This organism appears to have acquired in the struggle for existence 
a place quite as advantageous as that of Rhizopoda with solid coverings, 
for on occasion its pseudopodia function as true spines, and it is con- 
sequently left unmolested by Rhizopods, Infusoria, and Rotifers, while, 
on the other hand, it makes considerable ravages among the last tw'o of 
these groups. 
The nucleus is quite unlike that which one is in the habit of seeing 
in the lower animals, for it has a vesicular structure. There is an 
external enveloping membrane which bounds a clear and apparently 
liquid mass, which itself surrounds a nucleus that is either rounded or 
has a slightly irregular contour. The author discusses the reasons for 
and against the view that the nuclear capsule is not part of the true 
nucleus, and decides in favour of the view that it is not. 
Discuss'ng the phenomena of reproduction, M. Penard points out 
that young examples differ a good deal among themselves; some are 
exactly like the adult, others have no vacuoles, the ectosarc forms a 
definite border, and the pseudopodia are almost always very fine, and 
much elongated ; others have a non-vacuolated ectosarc which is not 
distinguishable from the endosarc, very short pseudopodia, and a well- 
marked body-contour ; others differ from these last in having the 
pseudopodia fine and very long. In others, lastly, there are large 
rounded vacuoles around the nucleus, and the j)seudopodia are very fine 
and much elongated or wanting. The author differs from Gruber in 
stating that the young examples always have a distinct nucleus ; the 
error of Gruber is explained by the supposition that he has mistaken 
specimens of Cilioplirys, which look like young Actinophrys, but have a 
very obscure nucleus. 
The description given by Biitschli of the mode of formation of 
colonies would appear to be correct. A very interesting phenomenon is 
that which is called “ gelification ” ; the whole of the colony becomes 
transparent, and the ectosarc forms a hyaline mucilage around the 
clarified endosarc. If the formation of colonies has nothing to do with 
the direct reproduction of the individual, it is at least useful as infusing 
new forces into the animal ; the agglomerated individuals fuse so closely 
with one another, and their protoplasm anastomoses so completely, that 
when a specimen separates it must carry away with it part of the general 
mass, while leaving behind a little of its own. 
Division certainly occurs, and is perhajis less rare than it appears, 
for it is effected very rapidly and in darkness. In conclusion, the 
author has some observations on zoospores, budding, and encystation. 
The author agrees with Brandt that certain Saprolegnise parasitically 
infest Actinophrys, and he gives a short account of his own observations 
on them. 
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