DEVELOPMENT OE PEEIPATUS CAPENSIS. 
761 
are readily killed by immersion for four or five hours in water; and when thus treated 
they die in an extended condition, and are obtained in the most favourable condition 
for dissection or preservation in alcohol as museum specimens. They are apparently 
paralyzed after immersion for only a quarter of an hour in water, and remain extended 
and motionless, but they soon recover when placed again in the air. They can also be 
killed in an extended condition by being placed in a weak solution of chromic acid ; 
and this is the best method of commencing to harden them for the preparation of 
sections. 
Anatomy. 
Only those points in the anatomy of Peripatus will here be dwelt upon in which 
correction of former accounts appears to be necessary, or those which have been 
hitherto entirely unnoticed. No attempt will be made at a description of the whole 
structure of the animal. 
Digestive System . — The intestinal tract of Peripatus is described by Grube as straight 
and enlarged in each segment of the body. This is far from being the case, at least 
in the Cape species. The digestive tract is here longer than the body, and in all the 
specimens which I have examined has been considerably distended, so that it protruded 
itself in a loop, together with the attached slime-glands, from the first incision. The 
digestive tract is displayed in Plate LXX1I. fig. 1 *. It commences as an ovoid mus- 
cular pharynx, which is separated by a short contracted oesophagus from the elongate 
and capacious stomach, from which a very short piece of intestine or rectum leads to 
the anus. 
From the posterior part of the lateral surfaces of the pharynx arise a pair of small 
muscles, which probably are protractors of the pharynx, and serve to push forwards the 
jaws. The under surface of the pharynx, and also of the rectum, receive a large and 
conspicuous supply of tracheae: these are shown in the figure. The division between 
the stomach and intestine is much more marked in some specimens than others, and is 
best seen in quite fresh ones, where the stomach is distinguished by its pale pink 
colour. In some specimens there is a distinct shoulder at the point of junction. The 
wall of the stomach is plicated, and the organ has a convoluted appearance. In many 
specimens the stomach was folded in a single short dorsal loop, at about the junction 
of its first with its second third. The loop lies folded flat over the upper surface of 
the succeeding part of the stomach. It lies in the middle line, and is not at all inclined 
to either side. It was only about half an inch long, and was not observed in all speci- 
mens, but is probably always present when the body is in the contracted condition, 
since the excess in length of the intestinal tract over that of the body necessitates a 
folding of some kind. As Mr. Trimen, Curator of the Cape Museum, who long ago 
watched the habits of Peripatus , has pointed out to me, the great power of extension of 
* The beautiful drawings in Plate LXXII. were made for me from my dissections by Mr. J. J. Wild, Artist 
to the ‘ Challenger ’ Expedition. 
5 K 2 
