tion. These equatioiLs are piuely tliooretical, but the sorios is 

 interesting in that it sliowa a possible link between the prodne 

 tion of lactic and valeric acids. 



Glucose 



= 2 CjHoO;, 



Lactic acid 



CH3.CIIOH.COOH I 

 CH3.CHOH.COOH f 

 2 Lactic acid 



Dismutation 



and 

 dehydration 



Pyruvic acid 

 ( CHn.CO.COOH 

 ( CHs.CHj.COOH 



Propionic acid 



+ H:0 



CH..CH».COOH 



t'Hn.CO.COOH + CHuCHo.COOH = CHa.COH.COOH 

 CH,a'HOH.CH=.CH2.COOH + CO: 



-, Hydroxy-valeric aeid 



CH3.CH0H.CHs.CH..C00H 



= CH3.CH2.CH2.CH2.COOH 4- 

 Normal valeric acid 



1 CoH„0„ = 1 CH..CH..CH0.CH2.COOH + HjO + CO2 + O 

 12 C«H,=Oe =12 CHr,.CHo.CH!.CH:.COOH + 12 H:0 + 



1 C„H„Oo + 6 0= 



12 CO. + 6 O2 

 6 CO2 + 6 H=0 



13 CoH,.0„ = 12 CH::.CH...CH=.CH2.COOH + 18 CO2 + 18 H2O. 



In effect, then, 12 molecules of sugar would be transformed 

 into 12 molecules of valeric aeid, carbon dioxide and water, 

 and the oxygen liberated during this process would be sufficient 

 to oxidize completely a thirteenth molecule of sugar. 



Toryu (1936a) proposed the equation: 4C„Hi:08 = 400. + 

 4C.'iHio02 + H2O. This equation needs no further considera- 

 tion, since the O and H atoms on the two sides do not balance. 

 Correctly written it would read: 4CoHi-0,; = 400: + 4CgHio02 

 + 4H;0 + 20=. This obviously corresponds closely to an inter- 

 mediate step of Koenigs' equation as formulated by Jost. 



The amount of heat produced during the metabolism of 

 Ascaris lumbricoicles was first determined directly by Krum- 

 macher (1919). His experiments, however, were performed at 

 a time at which o.xygen was regarded as an inert gas for these 

 worms. Krummacher's experiments were neither clearly aerobic 

 nor anaerobic, and the data obtained are therefore difRcult to 

 interpret. Meier (1931), on Krummacher's suggestion, per- 

 formed similar experiments under anaerobic conditions. He 

 found a heat production of 0.300 gm cal per gm of worm per 

 hour. On the basis of Weinland 's chemical data and his own 

 heat determinations he calculated that the fermentation process 

 yields 22 percent of the energy obtainable by total oxidation 

 of the carbohydrate. This is considerabl.v more than usually 

 found in bacterial fermentations. Undoubtedly, however, Meier 's 

 figure of 22 percent is far too high. His experimental periods 

 lasted only from 4 to 12 hours, and he used presumably fresh 

 worms. Therefore, the carbohydrate consumption must have 

 been much higher than Weinland 's figure. Furthermore, Schulte 

 (1917) has demonstrated by direct comparisons of the heat of 

 combu.stion with the glycogen content of fresh and starving 

 ascarids that the carbohydrate metabolism accounts for only 

 80 percent of the total loss of calories from the body. Meier, 

 however, assumed that the total heat production was due to 

 carbohydrate fermentation. At present the data necessary for 

 an e.xact balance sheet of the energies involved seems to be 

 unavailable. A fair guess .would place the energy yield of the 

 fermentation between 6 and 12 percent. This is still more than 

 that usually found in bacterial fermentations. Lactic acid fer- 

 mentation, for example, yields only about 2.6 percent, and al- 

 coholic fermentation yields 4 percent. 



Changes under anaerobic conditions in the material extract- 

 able with ether have been studied less thoroughly than the 

 changes in glycogen content. Weinland (1901) found that 

 there was no change in the fat content of ascarids during star- 

 vation, and V. Brand (1934a) reached the same conclusion. 

 Schulte (1917), on the other hand, observed a fat increase of 

 0.08 gm per 100 gm animals per day. He considered this fat 

 to be a product of carbohydrate fermentation. It seems cer- 

 tain, at least, that no fat is consumed under anaerobic condi- 

 tions. This is not astonishing, because it seems hardly possible 

 that an anaerobic process could yield energy from an oxygen 

 poor substance like fat (Weinland, 1901). 



The nitrogen metabolism of Ascaris is not very great. For 

 100 gm of worms the amount of nitrogen excreted in 24 hours 

 was found by Weinland (1904b) to be 15 to 20 mgm and by 

 V. Brand f 1934a) to be 29 mgm. One third of the excreted N 

 is ammonia, and the greater part of the remainder can be 

 precipitated by phosjjhotungstic acid (Weinland, 1904b). Flury 

 (1912) found that the worms excreted not only ammonia but 

 small amounts of amine bases, substances which gave the 



biuret reaction, hydrogen sulfide (also Kniger, 1936), and 

 mercai)tan. According to v. Brand (1934a) about one fourth of 

 the total excreted N is contained in discharged eggs. Chitwood 

 (1938) found urea in a concentration of about 0.02 percent in 

 the tiuid from the excretory pore of freshly collected worms. 

 .\ftcr 24 hours of starvation the tests for urea were negative, 

 and Chitwood doubts that the urea was formed by the worm. 

 It may have been obtained from the host. 



METABOLISM UNDER AEROBIC CONDITIONS 



Weinland (1901) believed that Ascaris did not consume oxy- 

 gen. However, he did observe that more carbon dioxide was 

 evolved under aerobic than under anaerobic conditions. He 

 explained this on the assumption that the extra carbon dioxide 

 was due eitlier to the metabolism of ;ierobically developing eggs 

 or to that of an aerobic bacterial flora. His view was generally 

 accepted until Adam (1932) proved that Ascaris was able to 

 consume oxygen. The observations of Adam were soon con- 

 firmed and extended to other forms. The following table sum- 

 marizes some of these data on oxygen consumption. 



O2 consumption in 

 gm per 100 gm 

 worms in 24 hrs. 



The oxygen consumption of both Setaria and Ancylostoma is 

 considerably higher than that of Ascaris or Parascaris. The 

 former undoubtedly have easier access to oxygen and may 

 therefore be better adapted to aerobic metabolism. 



The amount of oxygen consumed by Ascaris is influenced by 

 several factors. One factor is size, and small animals consume 

 relatively more than large ones. However, it is doubtful if the 

 difference in oxygen consumption of males and females can be 

 explained merely on the basis of size. Kruger (1936) gave a 

 formula which allows one to calculate approximately the in- 

 crease of oxygen consumption with increasing weight. The 

 formula is applicable only to worms which weigh over 1.4 gm. 

 In smaller worms the increase is more rapid. Kruger stated 

 nothing about the sex of his worms, but the deviation of his 

 data from the formula begins near the average weight of males. 

 In a recent paper Kruger (1940) shows that the 0= consump- 

 tion of ascarids of various sizes is fairly constant if referred 

 to surface rather than weight. 



The oxygen consumption of starving ascarids kept for long 

 periods of time at the oxygen tension of air show a general 

 tendency to increase (v. Brand, 1934a; Kriiger, 1937). This 

 might be an indication of adaptation to the abnormally high 

 oxygen tension. 



The oxygen consumption of Ascaris varies directly with the 

 oxygen tension, regardless of whether whole worms, parts of 

 worms or even minced material is used (Harnisch, 1933; 

 Kriiger, 1936). This is a striking contrast to what is known 

 from massively built free-living organisms, like aetiuians. In 

 these a similar dependence is observed in whole animals, but 

 it disappears if minced material is used. The diffusion rate 

 of oxygen is the limiting factor, and if the path through which 

 oxygen has to diffuse is shortened by using minced animals, the 

 oxygen consumption remains virtually unchanged over a wide 

 range of tensions. This explanation can not hold for Ascaris. 

 Harnisch, however, has found that the oxygen consumption of 

 planarians and Chironomus larvae, which is normally indepen- 

 dent of oxygen tension, may become dependent if the animals 

 are subjected to anaerobic conditions prior to the experiments. 

 In his opinion two kinds of aerobic processes must be dis- 

 tinguished: (1) a primary aerobic process which is considered 

 to be independent of the oxygen tension, and (2) a secondary 

 process which is considered to be dependent. In Ascaris only 



'ICriiger (1936) gives data of various sized worms. Those for worms 

 of about the average size of males and females have been introduced in 

 the table, the higher figure being for worms of 1.5 gm. the lower for 

 worms of 4. .5 gm. 



363 



