262 PROGRESS OF MICROSCOPICAL SCIENCE. 
Amceba swallowing another, and appropriating its structure to its 
own, just as we might do a piece of flesh, completely, without there 
being any excrementitious matter to be voided. 
The Pollen of the Conifere.—The ‘Journal of Botany’ (Feb- 
ruary) states that in the recently published ‘Atti del Congresso 
Internazionale Botanico tenuto in Firenze, there is an interesting 
paper by M. Tchistiakoff on Coniferous pollen, illustrated by two 
plates. Whether the grains be deprived of or provided with an air- 
chamber, in both cases the extine is composed of two layers, which 
are formed simultaneously, by transformation of the two-layered pri- 
mordial utricle, where the air-chamber is absent; while in the other 
condition the layers appear successively, the primordial utricle being 
here very thin, and the inner portion of the extine being laid down 
from a peripheral layer of plasma which appears after the formation 
of the thin outer portion. At each point where an air-chamber is 
destined to appear is seen an interspace between the two layers of the 
extine, filled with a small quantity of a gelatinous hygroscopic sub- 
stance. By expansion of the elastic outer extine-layer the interspaces 
are converted into vesicles; these are seen to be filled with a watery 
fluid which soon disappears, and the air-chamber is complete. Mean- 
while the several-layered intine has been formed by a secretion of 
cellulose. ‘he internal changes are precluded by the dissolution 
of the starch, the contents of the grain becoming transformed into 
the fovilla; at this time the outer and inner layers of the intine 
appear more pronounced, and the intermediate ones more or less 
hygroscopic. The periphery of the fovilla then becomes organized as 
a new primordial utricle, composed sometimes of a dense, shining, 
prismatic, pavement-like plasma (of a number of crystalloids, in fact), 
which is very well seen in Sequoia, Cryptomeria, and Cunninghamia ; 
but in other cases the prismatic structure is less pronounced, or 
is found only locally on the circumference of the uncrystallized 
plasma. 
MicroscoricAL ConTENTS oF FOREIGN JOURNALS. 
The Journal de l Anatomie, publié par MM. Robin et Pouchet. 
No. 2, 1877. Paris: Germer Baillicre.—The first paper in this 
number of the Journal is one of considerable length, on a subject known 
to most of us. It is on the Demodex folliculorum, and is by M. Megnin. 
It deals -very exhaustively with the subject, going into the minute 
anatomy of the different forms of Demodex, of which four distinct 
woodeuts are given. The plate which accompanies the paper gives 
the entire structure, the magnification used varying from 300 to 1200. 
diameters. In one case a hair-follicle of a dog is represented which 
displays the hair, and almost within the hair-sac are to be seen more 
than twenty Demodices. The author traces the complete development 
of the animal through three of its larval stages, from the condition in 
which it is footless to its regular eight-footed stage. He also describes 
the different species of Demodex, and deals at some length with their 
habits. The article is specially remarkable for the attack which it 
