MINUTE ANATOMY OF THE BRACHIATE ECHINODERMS, 189 
at, as, unlike its homologue in the Ophiurids, it has no 
connection whatever with the muscles. It may possibly 
have some influence on the creeping movements which the 
isolated visceral mass has been observed to perform, but the 
movements of the organism as a whole are independent 
of it. 
These movements are effected by the contractions of pairs 
of muscular bundles (Pl. XII, figs. 14, 15, m.) which connect 
the successive joints of the arms, and sometimes also of the 
pinnules. Some tropical Comatule have from 50 to 200 
arms, each consisting of from 150 to 200 joints, and bearing 
a corresponding number of pinnules, the joints of which are 
also united by pairs of muscular bundles. Nevertheless, all 
this immense muscular system, the action of which is so 
perfectly co-ordinated when the animal swims, is generally 
supposed to be uncontrolled by any nervous apparatus. 
Fifteen years ago, however, long before the discovery of the 
ambulacral nerves, Dr. Carpenter suggested that the fibrillar 
envelope of the chambered organ and the axial cords of the 
rays and arms connected with it, constituted a nervous sys- 
tem governing the movements of the animal (2, 3,4). He 
was led to this view by the discovery that the axial cords 
give off pairs of branches which ramify upon the ends of the 
muscular bundles (fig. 14, a. m.). But in spite of the 
strong anatomical and physiological evidence in its favour, 
his suggestion has been by no means generally accepted. 
This is probably due to the morphological difficulties which 
it involves. Ludwig discusses it (19, 20) but declines to 
accept it, as he finds a difficulty in admitting that the 
Crinoids have an antiambulacral nervous system, of which 
we know as yet no homologue in the other Echinoderms. 
Nevertheless, he does not hesitate to regard the chambered 
organ and its connections as parts of a blood-vascular system, 
to which there is nothing comparable in the other Echino- 
derms. In the two leading German text-books! the nervous 
system of the Crinoids is described as essentially similar to 
that of the Asterids, and not a word is said as to the phy- 
siological importance of the axial cords, though in any other 
case the experimental evidence above mentioned would be 
at once admitted as a proof of their nervous nature. Both 
Claus and Gegenbaur, however, ignore it entirely. 
The branches of the axial cords which Dr. Carpenter 
traced on the ends of the muscular bundles are merely por- 
tions of a large system of branches connected with these 
* eg. Claus’s ‘ Grundziige der Zoologie ’ and Gegenbaur’s ‘ Grundriss der 
Vergleichenden Anatomie. 
