SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebbata and cryptogamia), 
MICBOSCOPY, Etc. 
Including Original Communications from Fellows and Others .* 
ZOOLOGY. 
VERTEBRATA. 
a. Embryology.f 
Theory of the Mesoderm.t — Dr* T. Garbowski discusses the theory 
of the mesoderm in the light of Amphioxus. His main conclusions are 
the following. The longitudinal axis of the larva and the dorsoventral 
axis of the gastrula are not at right angles, but diverge at an angle of 
about 70°. The gastrula of Amphioxus is no archigastrula, nor is the 
course of development palingenetic. Neither ectoderm alone nor endo- 
derm alone conditions the invagination, all the segmented material is 
concerned. The closure of the blastopore is not due to a longitudinal 
concrescence, but to a strong Nachwachsen , especially of the dorsal wall. 
At the posterior margin of the blastopore no primitive mesoderm 
cells are differentiated. The mitoses are not more crowded at the upper 
inturned margin of the blastopore than in other parts of the epithelium. 
The zone of the blastopore margin is, especially above, neither to be 
reckoned as ectoderm nor as endoderm. The upper wall of the arch- 
enteron is quite normal. There is no demonstrable connection between 
the anterior mesoderm folds and the blastopore. There is in Amphioxus 
no homologue of the “ peristomal ” mesoderm of Yertebrata. The meso- 
derm of Amphioxus is not genetically continuous with that of the 
Anamnia, and Amphioxus stands apart from other Chordata. 
Yolk-Sac of Scyllium.§— Herr Hs. Virchow describes the yolk-sac 
cleft and its closure ; the primary vascular relations (artery, vein, 
capillaries, and vascular islands) ; and the transition from the primary 
to the secondary vascular relations. 
* The Society are not intended to be denoted by the editorial “ we,” and they do 
not hold themselves responsible for the views of the authors of the papers noted, 
nor for any claim to novelty or otherwise made by them. The object of this part of 
the Journal is to present a summary of the papers as actually published , and to 
describe and illustrate Instruments, Apparatus, &c., which are either new or have 
not been previously described in this country. 
t This section includes not only papers relating to Embryology properly so called, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. % Anat. Anzeig., xiv. (1898) pp. 473-97 (4 figs). 
§ SB. Ges. Nat. Freunde Berlin, 1897, pp. 49-59. 
