SUMMARY 
OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY' AND BOTANY 
(principally Invertebrata and Crypto garni a), 
MICROSCOPY, &c., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS. 
ZOOLOGY. 
A. VERTEBRATA : — Embryology, Histology, and General. 
a. Embryology. f 
Germinal Layers in Vertebrates.j — Herr B. Lwoff distinguishes 
in the development of Amphioxus between the palingenetic invagination 
which forms the archenteron and the cenogenetic dorsal invagination of 
ectoderm which forms (he says) the rudiment of notochord and of meso- 
derm. In all cases these two processes can be distinguished. In no 
Vertebrate is the gut formed by invagination. The endoderm cells are 
grown round by the ectoderm, and the gut arises by a cleavage in the 
endoderm. All attempts to find dorsal and ventral gastrula-lips are 
far-fetched. Of one area, however, we may be sure, namely, that where 
the “ ectoblastogenic ” rudiment of notochord and mesoderm is formed. 
The neurenteric canal should be called a neurochordal canal, for that is 
what it is. The common origin of the nervous system and the rudiment 
of the notochord and mesoderm suggests affinity with Annelids in which 
there is a common neuromuscular rudiment. Herr Lwoff s most important 
contentions are (1) that the notochord and associated musculature have 
an ectodermic not endodermic origin, and (2) that with their rudiment 
that of the nervous system is associated. He promises to demonstrate 
this in detail ; the task, we should think, will not be an easy one. 
Development of Mammary Glands.§ — Prof. O. Schultze finds in 
embryos of pig, rabbit, mole, fox, and cat, that the first rudiment of the 
* 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. t Biol. Centralbl., xiii. (1893) pp. 76-81. 
§ Verh. Physik.-Med. Gesell. Wurzburg, xxvi. (1893) pp. 171-82 (2 pis.). 
