IS 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
SUMMARY 
OF CURRENT RESEARCHES RELATING TO 
ZOOLOGY AND BOTANY 
(principally Invertebrata and Cryptogamia ), 
MICROSCOPY, &c., 
INCLUDING ORIGINAL COMMUNICATIONS FROM FELLOWS AND OTHERS* 
ZOOLOGY. 
A. VERTEBRATA Embryology, Histology, and General. 
a. Embryology. f 
Development of Elements of Nervous System.^— Prof. A. Kolliker 
gives, in consideration of the present discussion on this subject, a 
summary account of his own views : — 
(1) The first nerve-fibres which appear in the tail-fringe of 
Batrachian larvae are all non-nucleated, very fine, branched filaments. 
(2) In time there appear on the filaments first a few, widely 
separated nuclei, which in time increase in number ; these are, for various 
reasons, to be regarded as mesodermal cells deposited from the out- 
side. 
(3) In fine medullated fibres there appear at the points of constric- 
tion very fine, non-nucleated, branched fibrils which are branches of the 
axis-cylinder ; these in time form fresh rich ramifications which are 
nucleated at points ; this, perhaps, shows in the most striking way that 
nerve-fibres are not derived from rows of cells. 
(4) All the peripheral larger motor nerve-trunks of Birds and Mam- 
mals are formed of bundles of very fine non-medullated nerve-fibrils 
which have no nuclei or cells and of an investment of mesodermal cells 
which gradually grows inwards. Prof. Kolliker has lately shown that 
the same is true of the sensory cephalic nerves of young embryos. 
This fact, again, shows clearly that these elements are not formed by 
the concrescence of rows of cells. 
(5) Further, the central nerve-fibres first appear without nuclei or 
* 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. 
f This section includes not only papers relating to Embryology properly so called, 
but also those dealing with Evolution, Development, and Reproduction, and allied 
subjects. 
j Verhandl. Anal. Gesell., 1892, pp. 76-8. 
