18709. | | Recent Literature. 695 
apparently untenable if we admit with Kolliker, which we ‘do not, 
that they are unicellular, while we deny that these cilia are direct 
prolongations of the cells which they seem to be so closely 
related to, we do not assert that they are always disconnected 
with some form of cell in the modern acceptance of the ideal cell. 
We do, however, believe that they are never the filiform prolifera- 
tions of a distinct cell-membrane, however much they may 
appear to be so, but that in such cases they arise from the cyto- 
blastema which overlies the cells.” 
That vibratile cilia are “ individualistic in their movements at 
times, just as an arm or aleg is individualized” is claimed by our 
author, who remarks as follows: “Cilia are commonly treated 
trolling the actions of any one separately. s well might one 
claim that the numerous legs of a centipede are not capable of 
individual control.” The beautiful figure given indicates the indi- 
viduality of the cilia, and that they are “individually con- 
trollable.” 
he memoir ends abruptly with an account of the lasso cells 
or prehensile cysts (nematocysts and colletocysts), by which, as in 
most other Ccelenterates, the prey is benumbed and thus rendered 
more easy of capture. In 1863 Clark published the opinion that 
the nematocysts “have an intercellular origin, and do not develop 
within the cells which form the layer in which they are imbedded, 
ut commence their career, de novo, by free-cell formation in the 
cytoblastema.” the latter term referring, as we understand it, to 
the protoplasm or parenchym of the body. Description is also 
assume that, as in all the other four grand divisions of animals, 
the mouth is at the cephalic or anterior extremity of the body, 
and that all the rest of the organism is virtually, if not really, 
topographically behind it, and that whatever extends from the 
oral end of the body dves not radiate from that end in two, three, 
four or five or more directions, but trends posteriorly in so many 
plane which divides the body into a bilateral figure. To give the 
idea a reality, we have but to point to the mouth of an Actinia 
1 Mind in Natnre, or the Origin of Life and the Mode of Development of Ani- 
mals, By H. J. Clark. D. Appleton & Co. 1865. ? 
