218 
POPULAK SCIENCE KEVIEW. 
pical Journal” [Feb.], by Mr. Cbas. Stewart. He says that the description 
these parts generally given is not quite correct ; the marginal spines do not 
stand out horizontally, but project forwards from the flat anterior surface; 
this arrangement seems to enable them to grasp the body to which the sucker 
is applied when its centre is pulled towards the animal. The part of the 
rosette nearest the animal is very complex, each plate showing a depression of 
great depth, so that the inner as well as the outer margin of the rosette is thin, 
the greatest thickness being found a little to the inner side of the centre of 
each plate. Just inside the outer margin of the depressed area may be seen a 
small extremely transparent tubercle ; it is upon this tubercle that the angles 
of the polygonal ringrest, and to the constant motion of the ring upon the rosette 
must be attributed the solidity and consequent transparency of the tubercle. 
The posterior contiguous edges of the plates of the rosette are bevelled off, so 
that their anterior diameter is greater than their posterior ; the result of this 
is, that when the posterior margins of all the plates are brought together the 
anterior surface of the entire sucker is rendered convex, and so becomes de- 
tached from the body to which it was fixed, whereas, when the posterior 
margins are separated, the front surface of the sucker becomes concave, and 
the marginal spines grasp like claws any inequalities of the body to which 
they are applied. 
Gundlachi’s Objectives will henceforth come from America instead of from 
Germany. We hear that Herr Gundlach has gone from Berlin to the 
United States. 
A Hcematozoon in Human Blood has been discovered and described by 
Dr. E. T. Lewis, in a book which he has published on the subject. It is 
published at the otfice of the Superintendent of Government printing at 
Calcutta. 
PHYSICS. 
Browning' s Panergetic Binocular Opera or Field- Glass. — This is a glass 
which we can honestly recommend as an excellent opera or field-glass, being 
admirable as the former, bringing out the figures with marvellous distinct- 
ness, and having a very large field of view. Used as the latter, its advan- 
tages are still striking ; for in the dusk of evening, or when a considerable 
deal of mist or fog is about, it brings out the objects with a very great deal 
of distinctness. There is but one slight objection, and that refers simply to 
its weight; however this is an objection that will occur to very few, and to 
those who can afibrd the Aluminium form it disappears at once. Its eye and 
field glasses being each compounded of three lenses, there are in all twelve 
glasses, so that chromatic and spherical aberration are largely counter- 
balanced. Altogether it has so very many advantages over the other 
Binoculars that we have seen, that we confidently award it very high praise 
indeed. 
Nature and Duration of Discharge of a Leyden Jar. — Prof. 0. N. Eood, 
who has investigated this question (“ Silliman’s American Journal,” Nov. 
1872), sums up his opinions as follows. He says that if a Leyden jar, of a 
selected size, with a fixed strikino- distance, be connected with an induction 
