Aspects of the Body in Vertebrates and Arthropods. 243 

 XXIX. — Aspects of the Body in Verfahrates and Arthropods. 



"Bj a. 8'. rACKARD*. 



Under the title 'Aspects of the Body in VertcLratcs and 

 Invertebrates ' (London, 1883) the venerable and distin- 

 guished English anatomist and palaeontologist, Professor Sir 

 Kichard Owen, renews in a vigorous way the old discussion 

 originally begun by Geoffroy 8t.-Ililaire. The view in 

 question is tersely presented in St. Ililaire's answer to Dugcjs, 

 quoted by Professor Owen, when he replied by reference to 

 "Fig. 2 de la septicmc ])lanehe: \A se trouve efFcctivenient 

 rcprescntc un homard couelie sur le dos et montrant distinctive- 

 ment ses visccrcs dans la position ou Ic sont Ics viscores dcs 

 niammiftjres places sur le ventre." This view was combated 

 by Cuvier, and in this respect he has been followed by 

 Gcgcnbaur. 



In his able essay Professor Owen jtlaccs himself on the 

 side of St.-Hilaire, and the si)ecial point in vertebrate anatomy 

 which he brings forward to siip])ort this opinion is the homo- 

 logy of the conario-hypophysial tract, which he regards as 

 " the modified homologue of the mouth and gullet of inverte- 

 brates ;" and at the end of chapter i. he concludes that " the 

 surfaces or aspects of the body which are truly homologous 

 in the snake and cater[)illar arc the Pleural and the lutinal^ 

 not the dorsal and the ventral^ 



In his second chapter, entitled " Cerebral Homologies in 

 Vertebrates and Invertebrates," Professor Owen quotes our 

 statementf that '' tlie brain and nervous cord of tlie fish or 

 man is fundamentally ditl'crent, or not homcdogous with that 

 of the lower or invertebrate animals," and then proceeds to 

 criticize it. 



The chapter on the Ijrain of the locust was written for the 

 unscientific as well as the scientific reader, and the introduc- 

 tory part was presented in a terse, perhaps dogmatic way, for 

 the sake of clearness. 



The author, without taking time and space to discuss at 

 length this broad question, which requires a far wider 

 acquaintance with anatomy and embryology than he claims 

 to possess, would beg leave to briefly present some facts and 

 considerations Avhich seem to him to support the view he 

 adopted as to the lack of homology between the nervous 

 system of Arthropods and Vertebrates. 



* From achance sheets of the ' American Naturalist/ Sept. 1884, 

 pp. 8o-")- t«jl, conin)uiii( ated by the Anthor. 



t Second Report U.S. Entomol(\L'"i<'al ('ommission, chap, xi., "The 

 Brain of the Locust," p. 224 (1880). '' 



19* 



