L.M.B.C. MEMOIRS. 



No. I. ASCIDIA. 



Professor W. A. Herdman, D.Sc, F.R.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 problems 

 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 



