[ 14 J 



III. 



EEVIEW OF DOHRN' S THEORIES ON THE ORIGIN OF 

 VERTEBRATES. By ROBERT F. SCHARFF, B. Bo., 

 Ph. D., Curator, Natural History Department, Museum of 

 Science and Art, Dublin. 



[Read December 14, 1887]. 



The only account, in English, of some of these " Studien zar 

 Urgeschichte des Wirbelthierkorpers " was published by Cunning- 

 ham in the Quarterly Journal of Microscopical Science, 1886. I 

 herewith propose to give a full resume of the subject, including the 

 most recent Paper, which was only issued a few months ago. 

 Those who have not seriously considered these new theories will, 

 no doubt, welcome an additional exposition before tackling the 

 original Grerman version, of which twelve parts have now been 

 published in the Journal issued by the Zoological Station at 

 Naples. 1 



In 1875, Dohrn wrote a small pamphlet " On the Origin of 

 Vertebrates, and the Principle of Change of Function." He, in 

 this Paper, drew attention to the fact, that in three chief points his 

 views differed from the current ideas. These were, the derivation 

 of vertebrates from worm-like ancestors, that the principle of 

 change of function was the best guide in tracing morphological 

 histories, and that degeneration might proceed to an unlimited 

 extent. 



The fundamental idea contained in the above-mentioned Paper 

 was that the ancestral vertebrate possessed an " oesophageal 

 nerve ring," similar to what we find at present in most of the 



1 Mittheilungen d. Zool. Station Neapel: " Studien zur Urgeschichte d. Wirbelthier- 

 korpers," by Anton Dohrn. Part i. vol. iii. 1882, pp. 252-263. Part n. vol. iii. 1882, 

 pp. 264-279. Part in. vol. iv. 1883, pp. 172-189. Part iv. vol. v. 1884, pp. 102-151. 

 Part v. vol. v. 1884, pp. 151-160. Part vi. vol. v. 1884, 161-195. Part vn. 

 vol. vi. 1885, pp. 1-48. Part vin. vol. vi. 1885, pp. 49-92. Part ix. vol. vi. 

 1885, pp. 399-431. Part x. vol. vi. 1885, pp. 432-480. Part xi. vol. vii. 1886, 

 pp. 128-176. Part xn. vol. vii. 1887, pp. 301-337. 



