153 
SUMMARY 
OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY AND BOTANY 
(principally Invertebrata and Crypto gamia'), 
MICROSCOPY, Ac., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS * * * § 
ZOOLOGY. 
A. VERTEBRATA: — Embryology, Histology, and General. 
a. Embryology. f 
Experimental Embryology4 — Dr. W. Roux gives an account of the 
experiments which he, Chabry, Driesch, Fiedler, Hertwig, Chun, and 
others have made in regard to the development of one of the two first 
blastomeres of an ovum. Discrepancies in detail there may be, but 
this general result seems certain : in Chordate, Echinoderm, and Coelen- 
terate types it has been shown that from one of the first two segmenta- 
tion-cells, separated from or bereft of its neighbour, a typical half- 
development or hemiplast results, and that from this, at an early stage 
in ova with little yolk ( Echinus , Ascidia ), at a later stage in ova with 
a considerable amount of yolk ( Bana , Ctenophora), there results a 
“ post-generation ” of the deficient half-body, a complete “ hemiooholo- 
plast ” or “ microholoplast.” 
Herr C. Herhst § has made numerous interesting experiments showing 
the (indirect) influence of the chemical composition of the medium on 
the development of sea-urchin ova. In a mixture of 1860 ccm. sea- water 
and 140 ccm. 3*7 per cent, potassium chloride solution, the formation of 
the calcareous needles in the larvae was delayed, they were eventually 
formed to a slight extent but abnormally, the characteristic pluteus- 
processes were not formed, but otherwise the larvae were normal. 
Probably the absence of the supporting needles involved the absence of 
* 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. X Yerhandl. Anat. Gesell., vi. (1892) pp. 22-62. 
§ Zeitschr. f. Wiss. Zool., lv. (1892) pp. 446-518 (2 pis.). 
1893. 
M 
