QUARTERLY CHRONICLE. 161 
membrane is very flexible, and is frequently made to undu- 
late, apparently by the successive impacts of the vibrating 
cilia. ‘The apparently most important members of the 
adherent organs are the hooks. ‘They vary in number from 
twenty-two to twenty-four, and curve in a direction which 
is diametrically opposite to the upward coil of the vibratory 
organ; 2. é. they are leotropic. They are separate pieces, of 
an L-formed shape, the upright part of the Z being the hook 
proper, and the horizontal limb the base of it. These hooks 
are arranged in a circle, with their horizontal limbs all 
pointing one way, and nearly or quite touch each other, 
according to circumstances. Immediately within the row of 
hooks a series of nail-shaped pieces extends in a circle, and 
they are arranged in such order that each one lies opposite 
the horizontal part of a hook. The tip of the nail-head pro- 
jects between the point of the succeeding nail and the base 
of a hook, the two latter constituting a sort of socket in 
which the former appears to slide. This would seem con- 
clusively to show that this complicated ring may be enlarged 
or diminished at the will of the animal. Faint radiating 
ridges, occupying the central two thirds of the adherent 
apparatus, are attached one by one to the point of the nail- 
shaped bodies just mentioned, and at right angles to them. 
In dying specimens the adherent organ readily separates 
from the body en masse ; but shortly after the striated mem- 
brane loosens from the circle ‘of hooks, and they become dis- 
jointed. It is worth noting that, after a cursory examination 
of this radiate apparatus, Professor Agassiz was rash enough 
at once to pronounce Trichodina as the medusoid of Hydra, 
while at the same time he asserts that Vorticellide are simple 
forms of Bryozoa. Assuredly, Professor Clark remarks, if 
the one is a medusoid the others are, and if these are Bryozoa 
so is the asserted medusoid. Hence we should have Acalephan 
Bryozoa or Molluscan Acalephe. ‘'The rest of the paper de- 
scribes the digestive, circulatory, and reproductive organs in 
an equally careful manner. The contractile vesicle is a 
simple cavity, which performs its systole once in fifteen 
seconds. The paper is illustrated by two clearly drawn 
plates, and is a valuable contribution to microzoology. 
Quarterly Journal of Science.—A curious and interesting 
paper “‘ On Cells,” by Prof. Fick, of Zurich, appears in the last 
number of this journal, from which we quote the following 
passage : ‘ 
“1f it be once admitted that animation extends downwards 
into the lowest forms of the animal kingdom, then it is also 
admitted that there exist single cells, which are to be reckoned 
