442 DAVENPORT HOOKER 
that, not only may a very primitive type of swimming move- 
ment be developed, but that a type which is apparently fairly 
well coordinated may be exhibited by embryos in which no ner- 
vous connection is present between the cut ends of the spinal 
cord. This was noticed particularly in the case of several, em- 
bryos in which the reversed middle piece healed in a somewhat 
oblique position to the long axis of the embryo. These embryos, 
though they lived for a considerable time, long after some sort 
of nervous connection had been established in the majority of 
other specimens, did not exhibit any connections of a nervous 
nature between the ends of the reversed piece of the central nery- 
ous system and that contained in the head and tail region. 
Nevertheless, the S reaction in these embryos gave place to the 
usual uncoordinated swimming movement in due course, which 
continued to exhibit all the signs of progressive coordination 
which had been previously supposed to accompany the estab- 
lishment of nervous connections between the severed cord ends. 
These embryos of course never swam in a perfectly normal 
manner, but they developed the ability to move over relatively 
long distances. Their movements showed a considerable degree 
of synchrony between the different nervously isolated portions 
of the body and the head and tail regions took part in the move- 
ments. It is of course certain that there 1s no nervous con- 
nection through the skin in any such sense as Wintrebert (’04) 
supposed. Careful examination demonstrated that there are no 
nervous connections between the two regions of the body, be- 
yond the possibility of the innervation of a pair of myotomes on 
either side of the cut surfaces. That this possibility is not a 
probability is demonstrated by the fact that such nervous 
connections have never been observed in these embryos and that 
the heavy mass of notochordal connective tissue which grew 
out from the injured notochord in these specimens completely 
isolated the cut ends of the cord in the middle piece from the 
other portions of the body. It is much more probable that the 
tension on the skin of the embryo caused by the movement 
of the middle piece has brought about a direct mechanical 
stimulation of the myotomes of the head and tail regions which 
