ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 561 



characters" to purely somatogenic characters. That is, he alters the 

 basis of discussion. It is of minor importance, he says, whether the 

 change produced in the germ-plasm is brought about " physically " (i.e. 

 by direct action of the stimulus), or " physiologically " (i.e. by action of 

 the modified soma on the germ-plasm). It is sufficient to note the fact 

 that there are characters which can be experimentally established in one 

 generation and appear in the. next generation in the absence of the 

 modifying conditions. Since the controversy as to the transmission 

 of somatic modifications began, there have been few experiments, and 

 we have therefore peculiar pleasure in recording Kammerer's very 

 important work. 



Parthenogenetic Segmentation in Fowl.* — A. Lecaillon maintains 

 against Barfurth and others, that the unfertilised eggs of the fowl may 

 exhibit " a special segmentation which one can hardly designate other- 

 wise than as a parthenogenetic segmentation. The cells which result 

 from this segmentation may possess a nucleus of normal appearance and 

 capable of exhibiting the phenomena of mitosis." Very soon, however, 

 the cells degenerate and development stops. 



Early Stages in Development of the White Mouse, f — Ar. 

 Anikiew describes and figures the early stages of segmentation in the 

 ova of the white mouse. He found some with two polar bodies and 

 some with one. In the maturation and fertilisation stages there is a 

 marked polar differentiation, but this seems to disappear later on. It 

 may be indicated by the position of the large pronuclei and of the 

 nuclear figures. In the stage of the segmentation-spindle the proto- 

 plasm is marked by a special grouping of the nutritive particles in a sort 

 of annular layer around the mitotic figure, as is sometimes seen at an 

 earlier stage. 



A fine account J of the phenomena of maturation and f ertilisation in 

 the ovum of the white mouse has been given by H. Lams and the late 

 J. Doorrne. 



Very Young Human Ovum.§ — L. Frassi gives an account of a 

 young ovum in situ, discussing the decidua and its vessels, the lencocytic 

 infiltration, the limitation of foetal and maternal elements, and the 

 epithelial remains of the wall of the egg-chamber. He regards the 

 following as belonging to the embryo : (1) the cellular enveloping layer ; 

 (2) the" cell-pillars ; (3) the syncytium ; (4) the layer of Langhans 

 (four epithelial layers formed from the primary epiblastic trophoblast) ; 

 and (5) the mesoblast of the chorion. The cellular enveloping layer 

 retains the original trophoblast character and presses persistently upon 

 the maternal tissue. The author's bibliography takes the form of a 

 table showing what the various observers have said as to Langhans' 

 layer, the syncytium, the intervillous spaces and the villi, the mode of 

 fixation, the decidua, the giant-cells, the glands, vessels, fibrin, size of 

 ovum, etc. 



* C.R. Soc. Biol. Paris, lxiv. (190S) pp. 647-9. 



t Anat. Anzeig., xxxii. (190S) pp. 320-30 (7 figs.). 



X Arch. Biol, xxiii. (1907) pp. 259-365 (3 pis.). 



§ Arch. Mlkr. Anat,, lxxi. (190S) pp. 667-94 (1 pi. and ]7 figs.). 



Oct. 21si, 1908 2 P 



