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aimself in the most important points in agreement with that 
observer. 
EMBRYOLOGY.—Oellacher (‘ Die organischen Veranderun- 
gen des unbefruchteten Hiihner-Eies, Zeitschrift des natur. 
med. Vereins in Innsbruck,’ 1870; Centralblatt, May 27th, 
1871) has observed the remarkable fact that even in warm- 
blooded vertebrata, the first act of embryonic development, 
namely,segmentation, may take place independently of impreg- 
nation by male semen. ‘The author found in unimpregnated 
fowls’ eggs, the yellow spot composed to external observation of 
three zones, namely, of an outer homogeneous ring, an inner 
spotted one, and a central homogeneous spot. The two first 
are only condensed portions of the white outer layer of the yolk 
which here, going under the central spot, passes into the 
central process of the yolk. The central spot alone is the 
true germ, and this has the form of a biconvex body. Micro- 
scopical examination now shows the germ to be composed of 
small roundish angular elements arranged in several layers, 
and each with a yellow nuclear spot, as after impregnation. 
When seen as a flat object, the appearance is also very much 
like what Coste has described as that of segmentation in im- 
pregnated fowls’ eggs, namely, a mosaic of cells in the centre 
and radiating grooves passing to the circumference. Oa 
incubating eggs of this kind, the author first saw the ele- 
ments of the uppermost layer multiply, and those of the under 
layer become larger and finely granular; but then solution 
of the cells gradually took place. Such eggs are accordingly 
incapable of further development. Nevertheless the process 
described constitutes the first step, though an abortive one, to 
parthenogenetic development. Attempts at parthenogenesis 
and partial embryonic cell-formation in unimpregnated eggs 
have, however, been already observed. The author draws 
attention to the observations of Hensen on the eggs of 
rabbits, which unimpregnated, and within closed cysts, 
developed themselves into poly-nucleated protoplasmatic 
masses and fibres; and further to the memoir of Kupffer on 
Ascidia canina, in which creature there arises in the egg, 
before impregnation, a peripheral layer of epithelium, which 
later on, after impregnation, becomes the external covering of 
the animal. 
MICROZOOLOGY.—‘ On the production of Swarm-spores in 
Noctiluca miliaris,’ by Prof. C. L. Cienkowski. With two 
plates. (Max Schultze’s ‘ Archiv,’ 2nd part, 1871). 
The developmental history of the Noctiluca is very im- 
perfectly known up to the present time ; the multiplicatiou 
by division and production of internal buds is nearly all 
