54 Gen. Sub. 
I. GENERAL SUBJECTS. 
In abnormal conditions the ova of Limulus segment meroblastically and 
develop yolk blastopores ; Patten (408) . 
Great variation is a frequent occurrence in the early cleavage stages of 
Amphibian ova ; Jordan & Eycleshymer (262). 
Blaatomeres of Hydractinia separated at the two-celled stage develop 
half planulee ; Bunting (73). 
The planes of the Triton-embryo in relation to those of cleavage : 
variations, and displacements, yet normal results ; yon Ebner 
(137). 
Double or multiple embryos from one ovum : After fertilisation the 
ova of sea-urchins are placed in diluted sea -water ; they burst, and 
part projects ; but returned to normal water may develop into two or 
several embryos, according to the shape of the “ extra ovat ” ; Loeb 
(312). 
Influence of gravity and the formation of double monsters ; Sciiultze 
(495). 
Ova of Rana fusca , fastened to glass slides, fertilised, and inverted, 
develop into double monsters. A re-arrangement of the material of the 
inverted cell acts like a partial division, and double development occurs. 
Double individuals probably arise from imperfectly divided ovarian ova ; 
double monsters from a very slight division ; separate individuals from a 
complete division into separate parts ; Sciiultze (495, 498). 
Effect of gravity on developing frog ova : (1) Confirmation of Pfliiger, 
as against Roux. (2) Fixing ova in abnormal position between glass- 
plates results in abnormality proportional to difference between the 
normal ovum-axis (between dark and light poles) and the direction of 
gravity. Thus inversion is followed by equal cleavage, and very regu- 
larly by double monsters. (3) General argument : If definite modifi- 
cations in the influence of gravitation produce specific abnormalities, 
then the influence of gravitation is a condition of normal development ; 
Sciiultze (495, 498). 
Artificial production of double-formations in frog ; Sciiultze (497). 
Origin of double-formations ; Loeb (315). 
Origin of monstrosities ; Mitropiianow (362). 
Influence of cold on the germ ; Braem (62). 
Influence of cold on frog’s ova : Exposure to 0° even for fourteen days 
inhibits all development, but does not kill (until after complete gastrula 
stage), nor produce abnormalities. Hertwig’s results are not in agree- 
ment ; Sciiultze (496). 
A new method of pressing frog’s eggs ; Born (52). 
Segmentation under pressure ; Ziegler (590). 
Discussion of germinal layers and developmental mechanics in con- 
nection with budding in Ascidians ; Hjort (244). 
Proposals towards experimental evolution, mostly as regards hybridisa- 
tion ; Beiila (30). 
Formation of embryo of the frog with reference to experiments ; 
Morgan (377). 
