( 82 ) 
PROGRESS OF MICROSCOPICAL SCIENCE. 
Observations on Rhizopods.—Some investigations have been recently 
conducted on Rhizopods by Professor Leidy, who stated to the 
Philadelphia Academy, that last July, in the sphagnum swamps of 
Tobyhanna, Pocono Mt., Monroe Co., Pa., he noticed an abundance of 
a Rhizopod which he thought he had not previously seen, and which 
he at first supposed to be an undescribed species, but which he now 
viewed as a variety of Hyalosphenia ligata. From this, as previously 
described, it differs in the test being of a pale sienna colour, and per- 
haps of greater thickness, but otherwise is like it. The test is com- 
ressed pyriform, with the length and breadth nearly or about equal, 
and the thickness one-half. The lateral borders are obtusely rounded. 
The mouth is transversely oval. The sarcode is colourless, and 
attached to the inside of the test by diverging threads. The pseudo- 
pods are usually from two to three. Measurements -08 mm. long and 
broad, and +036 thick, with the mouth +02 broad and -008 wide. 
Others varied from *06 long and -08 broad, to -092 long by °064 
broad. In observing the Pocono variety of Hyalosphenia ligata, and 
the beautiful and well-marked species Hyalosphenia papilio, he de- 
tected an important point of structure which previously had escaped 
his notice. In the active condition of these, and other Difflugians, 
they are seen with one or more pseudopods extended from the mouth 
of the test, to the margin of which the sarcode is attached, as well as 
by diverging threads to various points of the interior of the test. The 
interval between the body of the sarcode and the interior of the test is 
occupied with water. The extent of the interval increases with the 
increase in number and extent of protrusion of the pseudopods, and 
also varies according to the degree of emptiness or repletion with food 
of the sarcode body. When the pseudopods are withdrawn into the 
mouth of the test, the mass of the sarcode expands in a corresponding 
ratio, and the threads of attachment to the inside of the test contract 
in length. The intervening water appears to be displaced through 
small apertures of the lateral borders and fundus of the test, which 
exist in numbers usually from two to half a dozen or more. 
The Early Development of the Mammalian Embryo.—Mr. E. A. 
Schifer, of University College, has contributed a valuable paper on 
this subject to the ‘ Proceedings of the Royal Society’ (No. 168); and 
we much regret that our notice of it has been so long “ crushed out.” 
The paper is upon only the early stages of development; but those 
who know anything of the subject of development are aware how very 
incomplete is our actual knowledge on these points. Mr. Schiifer 
noticed these ova in the cornua uteri of a cat which had been just 
killed. He observed five swellings in the cornua, and an equal 
number of corpora lutei in the ovaries; therefore he concluded that 
these swellings were ova. So removing the uterus, and placing it in 
a weak solution of bichromate of potash, he proceeded carefully to slit 
open the cornua under the fluid with fine scissors. As each one of the 
