34 Dr. P. H. Carpenter on the 



have done, that sections of the second radials show ten nerve- 

 cords, the shape of which varies according to the pLine in 

 which they are cut ; but on p. 549 these ten cords are de- 

 scribed " comme r^sultat d<5finitif du travail de division ac- 

 compH dans I'epaisseur des premiers radiaux ;" and the authors 

 further proceed to say that these cords correspond to the nerves 

 of the ten arms. As a matter of fact, however, these ten 

 cords in the second radials are really converging, and not 

 diverging from points of division in the first radials, and each 

 of them contributes nerve-fibres to two arms, as explained by 

 Ludwig, Marshall, and myself and not to one only, as implied 

 by Messrs. Vogt and Yung. The real division by which the 

 five (double) nerves within the rays form ten (double) nerves 

 within the arms takes place in the third and not in the Jirst 

 radials, as has been known for years past. Facts like these 

 may be verified by any one who will take the trouble requi- 

 site for accurate section-cutting along particular planes of the 

 calyx, and will further acquaint himself with the characters 

 and arrangement of the internal canals, so that he will not be 

 liable to errors of " orientation " like those into which Messrs. 

 Vogt and Yung have fallen. 



Reference has been made already to the axial radial canals 

 which are enclosed between the rosette and the radials of 

 ConiatuJa, and sometimes reach the ventral surface of the 

 centro-dorsal. Their character and relations were minutely 

 described by myself in 1879 *. They were shown in longitu- 

 dinal and in transverse section, and were clearly distinguished 

 from the five cavities within the central capsule, which were 

 first discovered by Dr. Carpenter f. He gave the name " five- 

 chambered organ " or " quinquelocular organ " to the struc- 

 ture which had been described by Miiller as a single-cham- 

 bered heart ; for he found it to contain " five chambers clustered 

 like the carpels of an orange round a central axis 3" and he 

 described these chambers as being surrounded by a fibrillar 

 envelope, which he regarded as nervous in character. Mar- 

 shall \, again, spoke of the cavity of the centro-dorsal as 

 lodging a sac divided by vertical septa into five radial com- 

 partments, and hence called the chambered organ ; and he 

 went on to explain how this is surrounded by a thick fibrillar 

 investment known as the " central capsule." Ludwig had 

 previously adopted the same terminology, and, in fact, he was 

 the first to speak of the chambered organ without the nume- 



* Trans. Liun. Soc. Lond. 2ad ser. (Zool.), vol. ii. 1879, pp. 77, 78. 

 t Phil. Trans. 1866, p. 738; and Proc. Roy. Soc. 1876, vol. juiv. 

 pp. 218, 219. 



X Op. cit. p. 510. 



