SUMMARY OF CURRENT RESEARCHES 
RELATING TO 
ZOOLOGY AND BOTANY 
(principally invertebrata and cryptogamia), 
MICROSCOPY, Etc. 
Including Original Communications from Fellows and Others * 
ZOOLOGY. 
A. VERTEBRATA : — Embryology, Histology, and General, 
a. Embryology. f 
Von Baer’s Law and the Significance of Ancestral Rudiments in 
Embryonic Development, t — Mr. A. Sedgwick recognizes that von 
Baer’s law, that embryos of different members of the same group are 
more alike than the adults, and that the resemblances are the greater, 
the younger the embryos, is generally regarded as one of the fundamental 
postulates of zoological science. He sets himself to show that this view 
is not in accordance with the facts of development, and first takes the 
case of the fowl and the dog-fish ; he cites the chief points of difference 
between them, and sums up the comparison by saying that a blind man 
could distinguish between them. It is, of course, freely admitted that 
there are striking similarities between them, but it is questioned whether 
the differences, when set off against them, leave sufficient to justify 
Baer’s law. That law should, therefore, be replaced by the following : 
“ Embryos of different members of the same group often resemble one 
another in points in which the adults differ, and differ from one another 
in points in which the adults resemble ; and it is difficult, even if pos- 
sible, to say whether the differences or the resemblances have the 
greater zoological value, since we have no clearly defined standard of 
zoological value.” 
Again, if von Baer’s law have any meaning at all, animals so closely 
allied as the fowl and duck would be indistinguishable in the early 
stages of development ; yet the author says he can distinguish a fowl 
* 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. X Quart. Journ. Micr. Sci., xxxvi. (1894) pp. 35-52. 
