Pvieb.Cc. MEMOIRS: 
No. I. ASCIDIA. 
BY: 
Professor W. A. Herpman, D.Sc., F.B.S. 
ALTHOUGH the Ascidian has been much talked of and 
written about during the last quarter of a century, com- 
paratively few people, beyond the circle of professional 
biologists, have an accurate idea of what the animal is like 
in appearance and structure, or have more than a vague 
notion as to what the popular impression of its relation- 
ship to higher animals is based upon. 
The adult or fully-developed Ascidian is a very remark- 
able animal, and presents numerous interesting probiems 
for the biologist to investigate ; but its reputation is due, 
not to any of these, but to certain changes which the 
young animal undergoes in its development from the egg ; 
changes so remarkable and interesting that when the more 
important of them were discovered by Kowalevsky, some 
thirty years ago, they gave rise to the belief that Ascidians 
were a group of animals holding a position between the 
Vertebrata and the Invertebrata, and indicated a possible 
line along which the former might have been evolved from 
the latter. The opinions of scientific men on this point 
have undergone a certain amount of modification during 
