1866. ] Zoology, Animal Physiology, &. 131 
Rhbynchonella Geinitziana, which Dr. Carpenter describes as imper- 
forate as regards the outer layer, while Professor King declares 
it to be perforated. Dr. Carpenter expresses himself fairly 
enough, as prepared to meet with perforated Rhynchonellide, 
although imperforation is the family character; but a careful 
examination with the binocular microscope and a magnifying power 
of 120 diameters upon transparent lamellz and sections, makes him 
feel justified in reiterating his statement that the passages which are 
visible in the shell, traverse the internal layer only, and are therefore 
pits and not canals, while it appears that Prof ssor King’s observa- 
tions have been made upon the exposed surfaces of his specimens, 
with a Stanhope lens only. It does certainly appear to us pre- 
sumptuous, to say the least, in any observer to be content with 
such imperfect appliances and inadequate observation, to challenge 
with such boldness the results of so careful and trustworthy an 
observer as Dr. Carpenter. Inasmuch, however, as this is the third 
ease of a similar kind in which Professor King has come into 
collision with Dr. Carpenter, we cannot help fearing it is the result 
of an antagonism which, for Professor King’s reputation, is much 
to be regretted. 
Dr. Beale states that the best way of studying muscular con- 
traction is to examine the larva of the flesh fly. The movements 
continue for ten minutes or a quarter of an hour after the muscles 
are detached from a freshly killed larva, and in winter for as much 
as half-an-hour. The best way to see them is by polarized light, 
by the aid of a plate of crystallized gypsum. When the body colour 
is green, the waves of contraction which are propagated along each 
muscular fibre in different directions are of a brilliant purple. In 
other parts of the field the complementary colours are reversed. 
With very high powers, it is easy to observe the change which 
takes place in the contractile tissue itself, each time that it passes 
from the state of contraction to that of relaxation, and back again, 
and that for several minutes at a time. 
Mr. H. L. Smith of Kenyon College describes in ‘Silliman’s 
Journal’ an apparatus by means of which he keeps Diatomacexe 
alive for a long time under the microscope, for the purpose of 
observing the phenomena of conjugation. It is a slide, which is a 
trifle more than an eighth of an inch in thickness, and consists of 
two rectangular glass plates, 3 inches by 2, and zsth inch thick ; 
separated by thin strips of glass of the same thickness, cemented to 
the interior opposed faces, thus forming a closed cell to be filled 
with water, and upon which the achromatic condenser can be 
brought to bear. A small hole is drilled through the upper plate, 
and one corner of the upper glass is removed. The space between 
the two plates is then to be filled with clean water by means of a 
, K 2 
