Tlio (lata of Fries (liHUi) slmw tliat tlif gasos of man iiu a 

 mixed diet are similar to tliose given above for a meat diet. 

 Further analyses are given hj Baseli (190S). The absorption 

 of intestinal gases is diseiissid liy Melver, Redfield, and Bene 

 diet (192(i), and the subjeet of human gastro intestinal gases 

 is reviewed bv Ziegler and Ilirseh U!l2r)) and Lloyd-Jones aiiil 

 Liljedahl (l!t"34). 



The intestinal gases of the dog were analyzed by Planer 

 (ISlilO. His analyses demonstrated large amounts of CO2 and 

 N;, and a smaller amount of Hi; througluiut the digestive traet, 

 a small amount of 0» in the snuill intestine, and a small amount 

 of HaS in the large intestine when the dog was on bread or 

 meat diets. On a vegetable diet 11= largely replaced the N-, 

 while O2 and "US were absent. In these analyses methane is 

 conspicuously absent. 



The intestinal gases of various herl)ivores have been ana- 

 lyzed by Tappeiner (18S3), and the literature is summarized 

 by Scheunert and Sehieblich (1!127). The data of Tappeiner 

 (1883) on the percentage composition of the gases in cattle, 

 sheep, and goats (all of which were quite similar) are as 

 follows : 



Table 13. — Oxygen Content of Fluid Intestinal Maxxi 



COa 

 Os - 



CH. 



Ha 



Rumen 



65 



.5 



30 

 0.6-4.7 



1-40 



Small Intestine 

 62-92 







.04-6.6 



0-37 



1 



Caecum 



and Colon 



about 30 







38.r)3 



2-6 



23-34 



Data for the horse (Tappeiner, 1883) are: 



Small Caecum 



Stomach Intestine and Colon Eectum 



COi. 75 15-43 55-85 29 



Os 0.57-76 0.14 



CHi 11-33 57 



H2 14 20-24 1.7-2.2 0.8 



Na 10 37-60 .9-10.0 13 



I>ata for the rabbit (Tappeiner, 1883) are: 



Caecum 



Stomach Small Intestine and Colon 



CO2 32 75 6 



O2 0.6 



CH. 2 21.0 



Hj 18 0.6 



N2 ._ 68 6 72 



Long and Fenger (1917) found a large amount of N2 (74 — 

 92'/i ) somewhat less CO2 (o — 28%), and about 5 percent Os, 

 but no methane or H2 present in the small intestine of hogs. 



The production ot methane is probably caused mostly by bac- 

 terial decomposition of cellulose, althougli the data of Ruge 

 indicate that it can also be produced b.v bacterial action when 

 the animal is on a meat diet. The analyses of Tappeiner and 

 others also indicate the presence of H2S in some cases. H-S 

 and Xa must be formed by the action of bacteria on protein. 

 Ammonia is also formed by bacterial decomposition of protein, 

 Ijut it is usually bound by the acids of the intestine. Most of 

 the CO2 is probably of bacterial origin, although in the duo 

 denum it may also be formed by the NaX'Oa of the pancreatic 

 juice and the acid of the chyme. The NH., and the CO2 of the 

 succus entericus are discussed by Herrin (1937). Most of the 

 intestinal gases are eliminated from the body by the lungs. 

 Tacke (1H84) found that 10 to 20 times as much of the in- 

 testinal gases of rabbits escape by means cjf the blood and 

 lungs as by way of the anus. 



The effect of the gases other than o-xygcn on intestinal nema- 

 todes is entirely unknown. Methane, H^, and N2 are probably 

 without either beneficial or harmful effects. The utilization of 

 o.xygen will be discussed in the part dealing with metabolism of 

 adult nematodes. The effect of CO2 is unknown. Since it is 

 incapable of further oxidation and since there is no evidence 

 of chemosynthesis in the nematodes, the only apparent effect 

 it could have would be the ad,justment of intracellular pH. 

 Since intestinal nematodes live in a medium usually saturated 

 with CO2 it is conceivable that they may depend on this sub- 

 stance as an intracellular buffer. Therefore, it may become 

 important to maintain a high CO2 content in in vitro cultures 

 (Cf. possible role in growth of intestinal protozoa, Jahn, 1934, 

 1936). It should be noted that Weinland (1901) found that 

 Ancarif: survived longer in vitro when the medium was satu- 

 rated with ('Oj. 



Part of 

 .\nimal intestine 



Oxygen in Number 

 volume per- of 

 cent mean deter- 

 and ( ) mina- 

 extremes tions 



Horse Sm. intestine 0.024 



(0.016 0.031) 

 Dog. ... Sm. intestine 0.028 

 Cattle Sm. intestine 0.013 



(0.00 0.02.-,) 

 Sheep Sm. intestine 0.012 



(0.00 0.025) 

 Pig .... Sm. intestine 0.083 



(0.00-0.35,s) 

 Cattle Lg. intestine 0.010 



(0.00 0.023) 

 Pig -. Lg. intestine 0,00 



Investigator 



2 Toryu (1934) 



1 V. Brand & Weise (1932) 



2 V. Brand & Weise (1932) 



4 V, Brand & Weise (1932) 



(i V. Brand & Weise (1932) 



3 V. Brand & Weise (1932) 

 1 V. Brand & Weise (1932) 



Table 14. — Oxygen Cont 



Oxygen in 



volume per 



cent mean 



Part of and ( ) 



Animal intestine extremes 



Horse. .-Sm. intestine 0.67 



(0.57-0.76) 

 Cattle..-Sm. intestine 0.00 

 Cattle -Sm. intestine * 



Goat- Sm. intestine * 



Sheep-...Sm. intestine * 

 Pig -Sm. intestine 5.5 



(1.2 14.2) 

 Pig Sm. intestine 4.2 



(0.4-8.2) 

 Dog Sm. intestine 0.2 



(0.0-0.7) 

 Horse.- Lg. intestine 0.07 



(0.000.14) 

 Cattle....Lg. intestine 0.00 

 Goat Lg. intestine 0.03 



(0.00-0.07) 

 Sheep-— Lg. intestine 0.00 

 Rabbit -Lg. intestine 0.62 

 Dog -Lg. intestine 0.00 



*Not enough gas for analysis. 



ent of Intestinal Gases 



iS' umber 



of 

 deter- 

 mina- 

 tions Investigator 



3 Tappeiner (1883) 



1 Tappeiner (1883) 



* V. Brand & Weise (1932) 

 » Tappeiner (1883) 



* V. Brand & Weise (1932; 

 9 Long & Fenger (1917) 



6 V. Brand & Weise (1932) 



8 Planer (1860) 



4 Tappeiner (1883) 



1 Tappeiner (1883) 



3 Tappeiner (1883) 



1 Tappeiner (1883) 



1 Tappeiner (1883) 



6 Planer (1860) 



HYDROGEN ION CONCENTRATION 



The pH of the stomach and intestine has been measured for 

 a large number of animals, and some of the representative data 

 ai'e listed in Tables ]."j and 16. Contents of the stomach of car- 

 nivores, omnivores, and herbivores with a simple stomach, and 

 of the abomasum of ruminants are distinctly acid in character 

 due to the secretion of hydrochloric acid. The rumen and oma- 

 sum vary from neutral to distinctly alkaline. The pH of the 

 duodenum is extrenu^ly variable but is usually acid because of 

 the introduction of HCI from the stomach. The pH of the re 

 mainder of the small intestine is less acid than the duodenum, 

 and there is usually a progressive rise toward neutrality or to 

 a slight alkalinity; the pH seldom reaches a value higher than 

 8.0 or 8.2. The colon and caecum of most animals are neutral, 

 slightl.y acid, or slightly alkaline. Some of the recent litera- 

 ture is reviewed by Lenkeit (1933). 



The pH of the intestine may be lowered b.v the administra- 

 tion of large quantities of lactose, especially if the diet is 

 low in protein. Robinson and Duncan (1931) found that the 

 pH of the rat intestine could be lowered about one pH unit by 

 the administration of 25 percent lactose with a low protein 

 diet (other literature is cited by these authors). In man it is 

 known that the acidity of the intestine may be considerably 

 decreased if large amounts of lactose accompanied by Lacto- 

 bacilltis aeidophiltis are ingested (literature cited by Kopeloff, 

 1926, and Frost and Hankinson, 1931). Comparable results 

 have been obtained with the domestic fowl (Ashcraft, 1933). 

 The direct addition of mineral salts such as NaCl, MgSO<, CaCU, 

 Ca(0H)2, CaSO., NaHCO:,, and NH.Cl to the diet may have no 

 effect on pH in experimental animals (McClendon et al, 1919; 

 Heller, Owens, and Portwood, 1935 ; Mussehl, Blish, and Ack- 

 erson, 1933). However, positive results with mineral salts have 

 been obtained by Robinson (1922), Shohl and Bing (1928) and 

 others. A deficiency of vitamin D is also known to cause tlie 

 intestinal contents to become alkaline due to lack of Ca ab- 

 sorption (Zucker and Matzner, 1923; Jephcott and Bacharach, 



357 



