The oxygen consumption of Ascaris or Farascaris eggs has 

 also been reduced experimentally by ultraeentrifuging and by 

 exposure to cyanide (Zawadowsky, 1926; Huff and Boell, 1936). 

 About 90 percent of the respiration was sensitive to cyanide, 

 and it seemed that ultraeentrifuging affected only the cyanide 

 sensitive respiratory mechanism. 



The respiratory quotient of Farascaris and Ascaris eggs has 

 been found to be below 1, and this indicates that, in contrast 

 to results on tissues of the adult worm, no fermentative proc 

 esses are present in the eggs. The respiratory quotient deter- 

 mined at the beginning of development was about .80, and. 

 with some variations in the ease of Farascaris, it increased 

 during the later stages to .92.98 (Faure-Fremiet, 1913a, 1913; 

 Huff, 1936). The total energy liberated by one Farascaris dur- 

 ing its development was 50 x 10" cal. (Faure-Fremiet, 1913). 

 Nolf (1932) found that the R. Q. of Trichuris decreased from 

 a value of 1.0 for the first 5 days of development to a value of 

 0.73 for the 8th to ir)th days. " 



In considering the chemical changes which occur in the eggs 

 of parasitic nematodes during their development, one must 

 distinguish clearly between processes which lead to the forma- 

 tion of the egg shells and ijrocesses which liberate energy. 

 The shells, as far as they are formed from the ovum, consist 

 essentially of the shell proper and the vitelline membrane. The 

 shell is composed of chitin in such species as Farascaris, Ascaris. 

 Dioctophyma and Enterobius (Faure-Fremiet, 1913; Szwejkow- 

 ska, 1929 ; Schmidt, 1936 ; Wottge, 1937 ; Chitwood, 1938 ; Jacobs 

 and Jones, 1939). The investigations of Faure-Fremiet (1913) 

 and Szwejkowska (1929) have demonstrated that in Ascaris 

 about half the glycogen stored in the oocytes was used to form 

 the glucosamine incorporated in the chitin. The latter has 

 shown in addition that 26 percent of the total nitrogen of the 

 egg was used during the chitin formation. 



The vitelline membrane of the eggs of these and other species 

 is of a lipoid nature (Faure-Fremiet, 1913; Zawadowsky, 1928). 

 Faure Fremiet considered it to be mainly ascaryl alcohol, 

 Wottge (1937) obtained a positive reaction for cholesterol. 

 and Chitwood (1938) and Jacobs and Jones (1939) demon- 

 strated that it gave sterol reactions. During the secretion of 

 this layer certain changes in the chemical nature of the ether 

 soluble substances, perhaps a saponification, seemed to occur. 

 The necessity for further studies is indicated. 



Chemical analyses of the egg indicate that both glycogen and 

 fat are oxidized, and these data are in accordance with the 

 above data on the respiratory quotient. Swejkowska (1929) 

 found in Farascaris eggs jnst after fertilization about 0.46 

 percent volatile fatty acid and 0..53 percent higher fatty acids. 

 After formation of the second polar body these suli- 

 stances had diminished to 0.34 and 0.36 percent re- 

 spectively. For the same period it was calculated that 

 in addition to the glycogen used in the formation of chitin an 

 amount of glycogen corresponding to about 2.7 percent of the 

 egg weight had disappeared. From Faure Fremiet 's (1912, 

 1913) experinients it would appear that both fat and glycogen 

 were used during the later developmental stages. All of these 

 experiments were conducted under aerobic conditions. Dyrdowska 

 (1931) found by the use of staining methods that the glycogen 

 content of Farascaris eggs kept under anaerobic conditions un- 

 derwent a slight diminution and that there was a marked de- 

 crease in the fat content. It seems desirable that this decrease 

 in fat content should be verified with quantitative chemical 

 methods since, as already stated above, it is difficult to under- 

 stand how processes which liberate energy from fat could 

 occur in the absence of oxygen. It should, furthermore, be 

 remembered that Faure-Fremiet (1913) gained the impression 

 that the amount of fat in anaerobically kept eggs tended to 

 increase. 



With the exception of the above mentioned shifting of nitro 

 gen from the ovum to the chitin shell, nothing is known about 

 the nitrogen metabolism of eggs. Szwe.ikowska (1929) found 

 no change in the total nitrogen content during the time of 

 maturation, and Kosmin (1928) found the same nitrogen con 

 tent (1.78 percent) in undeveloped and developed eggs. She 

 points out that this may be caused by the impermeability of 

 the vitelline membrane for protein degradation products which 

 consequently might accumulate in the interior of the egg shells. 



The fully developed embryo of Ascaris contains glycogen, 

 even in eggs which have been stored for 6 months (Stepanow- 

 Grigoriew and Hoeppli, 1926). This observation has a bearing 

 on Pintner's theory (1922) concerning the physiological reason 

 for the migration of parasitic worms through the host body 

 prior to life in the intestine. Pintner was of the opinion that the 

 chief function of the migration was to allow the worms to live 

 for a time under aerobic conditions. This would allow them 

 to accumulate a glycogen reserve which later on would enable 

 them to begin life in the anaerobic intestine. The above men- 

 tioned observation of Stepanow-Grigoriew and Hoeppli (1926) 



is not what one might expect on the basis of this theory. How- 

 ever, StepanowGriegoriew and Hoeppli (1926) and Giovannola 

 (1936) found a definite accumulation of glycogen during the 

 migration. 



The fact that glycogen is still present in old embryos also 

 indicates that the rate of metabolism in fully developed eggs 

 is probably very much lower than in the developing eggs, and 

 this problem seems worthy of quantitative consideration. 



The young larvae of Ascaris, on the other hand, have a high 

 level of metabolism, as evidenced by the investigation of Fen- 

 wick (1938). He found a preliminary phase of about half an 

 hour during which the newly hatched larvae showed a low 

 oxygen consumption. This he explained on the assumption 

 that they had not yet become sufficiently adjusted to the new 

 environment. Then followed an intermediate phase, lasting 

 about an hour, in which 1,000 larvae consumed ]3er hour 9.3 cmm 

 oxygen at 37° C. After this the oxygen consumption decreased 

 to a third level (0.928 cmm per 1,000) which was about 1/10 

 that of the second level. This new rate of oxygen consumption 

 was maintained throughout the rest of the exjicriments. Fen- 

 wick explained the high rate of the intermediate stage on the 

 assumption that It was caused by the removal of an oxygen 

 debt which the larvae had contracted while living within the 

 egg shells. An investigation of the respiratory quotient of 

 eggs containing infective embryos should prove helpful in an- 

 swering this question. 



The rate of metabolism of Trichinella larvae, according to 

 the data of Stannard, McCoy and Latchford (1938), was about 

 as high as that of Ascaris larvae in the third of Fenwick's 

 stages. At body temperature in T.vrode solution the Trichinella 

 larvae consumed 2.24 cmm oxygen per mgm dry weight per 

 hour. In saline the value was 1.70, and in Tyrode without 

 bicarbonate it was 1.78. The figures for 1,000 larvae in these 

 solutions can be calculated to be about 1.12, O.S,") and 0.88 cmm 

 oxygen per hour, respectively. The respiration was independent 

 of the oxygen tension in the range of 1 to 100 percent oxygen. 

 It was very sensitive to cyanide, but was stimulated by carbon 

 monoxide and paraphenylene diamine. The respiratory quotient 

 of the Trichinella larvae was always above 1, and the averages 

 were from 1.13 to 1.17. It seems probable that under aerobic 

 conditions some fermentations may take place, liut most of the 

 oxidative processes apparently proceed to completion. Fer- 

 mentation alone was sufficient to keep the worms alive under 

 anaerobic conditions, but apparently oxygen was necessary for 

 enabling them to move. 



The fermentation processes of the Trichinella larvae are 

 very interesting, since they lead not only to the formation of 

 carbon dioxide but to the formation of other as yet unidentified 

 substances which are known to be non acidic. In this respect 

 they differ from all the other helminths. It is remarkable, fur- 

 thermore, that substances like iodoacetate and others, which 

 rapidlj' inhibit alcoholic fermentation or muscle glycolysis, were 

 quite slow in their action on the anaerobic carbon dioxide pro- 

 duction of these larvae (Stannard, McCoy and Latchford, 19,38). 

 McCoy, Downing and A'an Voorhis (1941) showed that radio- 

 active phosphorus fed to tlie host penetrates rapidly into the 

 larvae. This observation indicates that tlie larvae may have an 

 active metabolism inside the cyst. 



The Trichinella larvae are clearly aerobic rather than an- 

 aerobic organisms. This is also true for the larvae of Enstron- 

 (/i/lidcs, investigated by v. Brand (1938). He found that these 

 worms survived much longer under aerobic than under anaero- 

 bic conditions. One hundred grams of worms in the presence 

 of oxygen consumed 0.3 gm of glycogen in 24 hours at 37° C, 

 and no organic acids could be found. ITnder anaerobic condi- 

 tions 0.9 gm glycogen was consumed and organic acids equiva- 

 lent to 30 ce n/10 acid were produced. The ratio between aero- 

 bically and anaerobically consumed glycogen was 1:3, a ratio 

 which places these worms intermediate between most free- 

 living worms which have ratios of about 1 :■" and Ascaris with 

 one of 1.0:1.3. 



The experiments mentioned so far were performed with larvae 

 which had been living under natural conditions in a host. From 

 free-living stages of parasitic nematodes data are only avail- 

 able for Ancfilostonm caninnni. McCoy (1930) found that the 

 oxygen consumption of infective larvae varied greatly with 

 the temperature. At 7° C. it was imperceptible, but in the 

 range of 17° C. to 42° C. the oxygen consumption increased 

 about 9 percent for every degree rise in temperature, and fol- 

 lowed an exponential curve, the b constant, of which was 

 1.0879. The actual oxygen consumption at 37° C. corresponded 

 to 0.47 cmm per 1,000 larvae per hour, a figure somewhat 

 lower, but of the same order of magnitude as those mentioned 

 above for Ascaris and Trichinella larvae. 



The free-living larvae of Xecator aniericanns, and Ancj/losio- 

 ma canininn seem to derive their energy primarily from fatty 

 substances stored in their body (Payne, 1923, Rogers, 1939), 

 and the amount of fat demonstrable seems to be 



366 



