THE ANATOMY AND DEVELOPMENT OF PERIPATUS NOVAE-BRITANNIAE. 29 



takes 110 food. During such periods life must be sustained by the absorption of 

 reserve nutrient matter, and it would probably be found, if the subject were investi- 

 gated, that the gastral epithelium undergoes profound changes and differs immensely 

 during a period of feeding from its condition during a period of rest. 



P. novae-zealandiae does not feed during the winter months (Hutton). In the colder 

 months, P. leuckarti becomes sluggish and remains for considerable periods without eating 

 (Steel). With regard to P. capensis, Moseley (14, p. 762) says "It is very possible that 

 the animals feed very little or not at all during the breeding-season, but rest, as does 

 Julus according to Newport, at the time of the production of the eggs." 



It is further possible that the nutrition of the free-living Peripatus is affected during 

 the moulting periods. Hutton's observation of the occurrence of the so-called reserve 

 teeth below those in actual use rendered it probable that moulting did take place in 

 Peripatus. This has now been finally observed by Steel (23). Steel obtained several 

 perfect casts from both young and adult individuals. He however did not observe how 

 often this ecdysis recurs. 



In my sections through a young post partum female of P. novae-britanniae, there 

 is no regular gastral epithelium at all, but nuclei occur in numbers irregularly distributed 

 in the gastral cavity in the midst of a mass of foreign, presumably ingested material. 

 I found a similar condition in a young male. From these observations I am led to the 

 following conclusion, which is of value only as a working hypothesis. During certain 

 periods the gastral epithelium is a regular columnar epithelium as described by Balfour, 

 and its cells contain abundant spherules of reserve nutrient matter. At certain other 

 periods, perhaps periods of rest, the gastral epithelium undergoes histolysis, and the 

 endoderm performs its function of digestion by a process allied to phagocytosis, its cells 

 having exactly the properties of the trophocytes which I have described above in certain 

 stages of the development of P. novae-britanniae. 



I have little doubt that in discharging its digestive function Peripatus is quite as 

 original as it is in every other respect 1 . 



The young female referred to above, in which I observed this extraordinary "wan- 

 dering endoderm," was the specimen in which the nephridial end-sacs were so capitally 

 preserved. 



With regard to the globules described above in late embryos of P. novae-britanniae, 

 the smallest of them are much smaller than Balfour's spherules but, as already stated, 

 they behave differently towards staining reagents. The largest globules in Stage XI 

 measure "0125 mm. in diameter, in Stage XII nearly '02 mm. Possibly the larger ones 

 are sometimes produced by coalescence of smaller ones, and this would account for their 

 larger size in Stage XII. 



Besides differing in chemical properties, the globules differ from the spherules in 

 their source, in that while the latter owe their origin ultimately to foreign ingested 

 matter, the former are derived from the maternal organism. 



Finally, with regard to the histolysis which my sections show in Stage XII, it is to 

 be noted that it takes place pari passu with the opening of the proctodoeum into the 

 gastral cavity. In Stage XI the proctodoeum still ends blindly. 



1 See Appendix. 



