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Show 52 HABITS OF WORMS. CHAP. I. testine were distinctly acid at a distance of 5 em. below the gizzard. Even with the higher herbivorous and omnivorous anima~s, the contents of the large intestine are acl~. ''This, however, is not caused by any aCid '~ secretion from the mucous membrane ; the " reaction of the intestinal walls in the larger " as in the small intestine is alkaline. It "must therefore arise from acid fermentations " going on in the contents themselves ... · " In Carnivora the contents of the coecum "are said to be alkaline, and naturally the " amount of fermentation will depend largely "on the nature of the food."* With worms not only the contents of the intestines but their ejected matter or the ' . castings, are generally acid. Thirty cast.l~gs from different places were tested, and w1th three or four exceptions were found to be acid; and the exceptions may have been due to such castings not Laving been recently ejected; for some which were at first a~id, were on the following morning, after bemg dried and again moistened, no longer acid ; * M. Foster, 'A Text-Book of Physiology,' 2nd edit. 1878, p. 243. CHAP. I. CALCIFEROUS GLANDS. 53 and this probably resulted from the humus acids being, as is known to be the case, easily decomposed. Five fresh castings from worms which lived in mould close over the chalk were of a whitish colour and abounded with calcareous matter; and these were not in the least ac~d.. This shows how effectually carbonate of hme neutralises the intestinal acids. When worms were kept in pots filled with fine ferruginous sand, it was manifest that the oxide of iron, with which the ()'rains of silex were coated, had been dissolve~ and removed from them in the castings. The digestive fluid of worms resembles in its action, as already stated, the pancreatic secretion of the higher animals ; and in these latter, "pancreatic digestion is essentially "alkaline ; the action will not take place "unless some alkali be present; and the :: ac~i~ity ~f an alkali~e juice is arrested by aCidrficatwn, and h1ndered by neutraliza" tion." * Therefore it seems highly probable that the innumerable calciferous cells, which are poured from the four posterior glands into the ali1nentary canal of worms, serve to * M. Foster, Ibid. p. 200. |
