360 Miscellaneous. 
are contained by the ambulacral tentacles, and a great number of 
which exist in the sensitive papille of these tentacles, which Lud- 
wig erroneously regards as hollow. 
This double connexion of the axial cords of the arms and the cirri 
with the organs of sense and those of movement confirms the opinion 
put forward by the English authors. But it must be added that 
the stellate cells which form the external covering of the cords are 
themselves in connexion with the cells of connective tissue which 
fill all the intervals of the calcareous trabecule of the skeleton of 
the animal, cells which themselves form a continuous network, the 
last meshes of which are connected with the cells of the epithelium 
of the arms. 
In accordance with the close relationships which exist between 
all the tissues of the animal, the nervous system consequently re- 
mains in a state of remarkable indifferentiation. However it may 
be, if we assume that the axial cords of the cirri and arms are, as 
indicated by their anatomical connexions, dependencies of the ner- 
vous system, the chambered organ must be considered the central 
part of that system in the Crinoids; and these are important con- 
clusions, the morphological consequences of which we shall reserve 
for future development. 
In the parts of the arms in process of formation the tissue of the 
axial cord does not differ from the three yellow cells which surround 
it. It is by their free extremities that the arms increase in length. 
There exists a sort of terminal bud, which soon divides into two at 
first identical parts: one of these parts grows rapidly, and becomes 
a pinnule; the other elongates more slowly, and becomes again 
divided; the half opposite the newly-formed pinnule becomes in its 
turn a pinnule, and the bud included between the two pinnules con- 
tinues this mode of division until the growth comes to an end. 
From this it results that the structure of the arms and that of the 
pinnules are at first identical. If the pinnule continues its evolu- 
tion it becomes a ramification of the arm, and in this way we 
explain the mode of construction of the multistylate Comatule. 
When the pinnule stops in its evolution it appears to be only a 
simple appendage ; it presents an ambulacral canal, and below this 
a general cavity, which is usually divided into two very unequal 
chambers by a transverse partition. This structure is also that of 
the very young arms, in which the inferior chamber is extremely 
small. When the genital apparatus is developed this structure be- 
comes more complicated. The large chamber of the general cavity 
is divided afresh into three cavities by the appearance of a horizontal 
floor and a vertical floor. At the point of junction of these two 
floors there is a canal occupied in great part by the genital rhachis, 
the ramifications of which in the pinnules become the ovaries or the 
testes. I have been able to trace all these modifications, and I pro- 
pose shortly to make them known in all their details.—Comptes 
Rendus, July 16, 1883, p. 187. 
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