SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(PRINCIPALLY INVERTEBIIATA AND ORYPTOGAMIA), 
MICBOSCOPY, Etc. 
Including Original Communications from Fellows and Others .* 
ZOOLOGY. 
VERTEBRATA. 
a. Embryology, f 
Origin of Vertebrates.^ — Dr. W. H. Gaskell returns to this lasting 
problem. The principles upon which he has investigated the matter 
are based upon the continuity of the evolutionary process. That is to 
say, wherever a variation of organs in the Vertebrate phylum has taken 
place in a well defined direction, then, by tracing the same curve a step 
further, we may arrive at the condition in the immediate ancestor of 
Vertebrates. This principle holds good whether the curve of variation . 
is an ascending or descending one, related, for instance, to tlie cerebellum 
or to the pineal eye. 
Dr. Gaskell considers the history of the Vertebrate central nervous 
system, of the skeletal system, of the muscular system, of the respiratory 
system and nerves IX. and X., of the thyroid and nerve VII., of the 
motor part of the fifth nerve, of the eighth nerve, of the cranial segments 
and nerves, of the heart and ventral aortue, of the alimentary canal ; and 
his general conclusion, with elaborate evidence which we cannot here 
summarise, is that the phylogenetic signpost points directly to Limulus 
and its congeners as ancestral to Vertebrates. In particular, his paper 
emphasises the resemblances between Ammocoetes and Limulus . 
The discussion which followed, in which Messrs. Sedgwick, MacBride, 
Harmer, Gadow, Bateson, Shipley and Bles took part, is a valuable 
record of expert opinion in regard to the problem at issue. Gaskell’ s 
summary of the most important criticisms is that the resemblances 
between Ammocoetes , on the one hand, and Limulus and Scorpions on 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. X Proc. Cambridge Phil. Sqc., ix. (1896) pp. 19-47. 
N 2 
