cosa. Hoeppli further stated that in Fiilleborn 's Laboratory no 

 cases had been found with the asearid, Toxocara canis, attached 

 to the dog intestine. Other workers on examining large num- 

 bers of horse intestines at slaughter houses always found 

 Parascaris equornm free in the lumen of the gut. 



Standard textbooks carry the statement that Ascaris Iximhri- 

 coides feeds on intestinal contents but gnaws at the mucosa. 

 This statement doubtless is due to the occasional finding of 

 reddish spots in the intestinal epithelium in cases of asearid 

 infection. While such spots occur occasionally, those who have 

 examined hundreds of mammalian and avian intestines which 

 contained numerous ascarids can testify that in the great ma- 

 jority of eases, no evidences of the adult ascarids attaching 

 the mucosa are available. 



As to certain Asearidoidea being attached to the intestinal 

 wall presumably for feeding, Guiart, cited by Hoeppli (1927), 

 found in the stomach of a dolphin the clear imprint of the 

 worms' lips in pit-like depressions of the mucous membrane. 

 Similar observations were made by Hoeppli (1927) on a Con- 

 tracaeciim sp. from a seal from northern waters. It is quite 

 possible that instead of being attached, the dying worms 

 pressed their anterior ends deeply into the mucous membrane 

 of the dead host. 



As to the food of ascarids, Archer and Peterson (1930), by 

 giving patients infected with Ascaris liiinbricoides a barium- 

 cereal-meal, found that the enteric canals of the parasites 

 showed string like shadows, indicating that the nematodes in 

 the host intestine had swallowed the barium. These observa- 

 tions indicated that Ascaris lumbricoides feeds on the intes- 

 tinal contents of man. 



Following this work, Li (1933a) fed to six dogs, positive for 

 ascarids, liquid Chinese ink or powdered charcoal twice a day 

 for several days. While most of the tests were negative, due 

 presumably to a vermicidal action of the charcoal, one dog 

 gave unquestioned positive evidence. The one female worm 

 from the dog 's intestine definitely showed charcoal and beef 

 particles in its enteric tract. In a subsequent series of tests, 

 Li (1933b) fed a mixture of powdered charcoal, clotted blood, 

 striated beef muscle and starch granules to experimental ani- 

 mals harboring ascarids as follows: Dog, Toxocara canis; cat, 

 Toxascaris leonina ; and chicken, Ascaridia (/alii. The re- 

 sults from the dogs gave no positive evidence ; that from the 

 cat showed that the worm intestine contained diarcoal, blood 

 cells, and beef particles. These findings were confirmed by 

 examination of paraffin sections of the worms. The results 

 from four chickens showed charcoal and beef particles in the 

 intestines of all worms including both male and female sjjeci- 

 mens. From similar experiments, in which starch granules 

 were substituted for powdered charcoal, all worms recovered 

 showed starch granules and some beef particles. 



To ascertain the nature of food of the chicken cecal worm 

 SeteraMs gallinac, Li (1933b) fed infected chickens powdered 

 charcoal and beef as l)efore. On examination, most of the 

 worms showed charcoal in the entire intestine. In further 

 studies, Li opened tlic intestines of Ancaris lumbricoides from 

 man and mounted tlie intestinal contents on slides for micro- 

 scopic examination. Wliile most of these contents could not be 

 identified, Li found in one specimen two Ascaris eggs and a 

 piece of striated muscle. The results of Li 's experiments 

 (1933a, 1933b) indicate that the intestinal contents of the host 

 constitute part of the food of Ascaris lumbricoides, Toxocara 

 cauis, Toxascaris leonina, of mammals; and Ascaridia galli and 

 Jleteralcis gallinac of fowls. 



The findings of Li and of other workers cited, while showing 

 tliat certain ascaroids take intestinal contents, do not pre- 

 clude the possibility that these nematodes may also feed upon 

 the intestinal epithelium. In a study of the food of the fowl 

 nematode, Ascaridia galli (Schneider), Ackert and Whitloek 

 (1935) deprived chickens infected with Ascaridia galli of food 

 by mouth; the experimental chickens were nourished by intra- 

 muscular injections of glucose. The results of the first series 

 of experiments on 141 chickens with worms of various ages indi- 

 dated that little growth occurred in the worms after the host 

 chickens were taken off the regular feed. In the second series 

 in which 96 additional chickens were used, Ackert, Whitloek 

 and Freeman (1940) used worm infections of one week's dura- 

 tion in the tests. Experimental and control chicks under com- 

 parison were of the same age and the developing worms were 

 from the same egg cultures. The results of this series of tests 

 were very uniform, namely, that in the chickens given only 

 water per os and intramuscular injections of glucose, the young 

 Ascaridia galli ceased growing whereas tlie worms in the regu- 

 larly fed control chickens made normal growth. These results 

 indicate that the large nematode of chickens wliose mouth parts 

 are very similar to those of mammalian ascarids, did not secure 

 nutriment from the intestinal epithelium of the host. These 

 nematodes may have fed to some extent on duodenal mucus 

 from the goblet cells but Ackert, Edgar and Friek (1939) 

 have shown recently tliat such mucus ninv contain an inhibitory 



growth factor for young Ascaridia tliat have been grown in the 

 culture media developed by Ackert, Todd and Tanner (1938). 

 This last group of workers prepared a salt-dextrose solution in 

 which young Ascaridia galli will grow. On the introduction of 

 mucus from growing chickens into the nutrient solution, the 

 cultured Ascaridia ceased growing, whereas the control worms 

 in the nutrient solution continued to increase in length. In 

 the glucose-injected chickens, the duodenal mucus, while con- 

 taining an inhibitory growth factor, may have afforded the 

 Ascaridia galli food sufficient for maintaining life, but not for 

 growth. 



The literature cites cases in which lilood has been found in 

 the digestive tracts of ascaroids. For example, Mueller (1929) 

 found blood in the intestine of Anisahis simplex and Guiart, 

 cited by Lievre (1934), saw some Ascaris whose digestive tracts 

 were full of blood. On the other liand, Lievre cited Brumpt 

 as having performed numerous autopsies to see if Ascaris 

 caused ecchj-motic spots on the mucosa. But Brumpt was un- 

 able to find such spots, and the intestinal contents of the worms 

 showed only chyme, never blood. 



Indirect evidence of blood as a nutrient of ascarids is avail- 

 able from the finding of haemoglobin in the worms' bodies by 

 such tests as the Benzidine blood test and spectroscopic analy- 

 sis. That the former is an unreliable test for blood has been 

 shown recently by Davey (1938). Using spectroscopic analy- 

 sis, Lievre (1934) found traces of haemoglobin in the intestine 

 of the dog asearid, Toxocara canis. Even though the spectro- 

 scopic examination of blood was positive in 7.') percent of the 

 cases, the quantity of haemoglobin noticed was so small that 

 Lievre was led to think that the haemoglobin had come from 

 the flesh colored food of the animal. Lievre, on macerating the 

 intestines of Ascaris lumbricoides, Parascaris equorum and 

 Ascaris suum was unable to find any haemoglobin present in 

 these worms by spectroscopic analysis. He concluded that there 

 is no haemophagia in Ascaris and only in exceptional circum- 

 stances would there be ingestion of blood. Davey (1938) dem- 

 onstrated haemoglobin in the dermo-muscular tube of Toxocara 

 canis and in tissues other than the alimentary canal of Ascaris. 

 He found, further, that the absorption bands of the haemoglo- 

 bin in the tissues had different positions from those in the 

 blood of their hosts, indicating that these nematodes were able 

 to synthesize haemoglobin. Thus the presence of haemoglobin 

 in the tissues of nematodes is not necessarily evidence tliat tliey 

 feed on blood. 



Further indicative evidence that ascarids may take blood is 

 available from the work of Schwartz (1921) who found that 

 the body fluid of Ascaris lumbricoides inhibited coagulation of 

 rabbit blood to a moderate extent. Extracts of Parascaris 

 equorum and of Toxocara sp. had a slight effect on the coagula- 

 tion of sheep's blood. Whether or not this property of the 

 asearid body is utilized by the living nematodes is unknown. 

 It is conceivable that asearid nematodes living with hookworms 

 which are known to draw l)lood in excess would swallow blood 

 from time to time. But as other writers have indicated, this 

 would be exceptional rather than normal. 



In the light of our present knowledge, it appears that tlie 

 oxyuroids and ascaridoids feed normally on the intestinal con- 

 tents of the host including also any mucus, desquamated muco- 

 sa cells, and blood elements that may be free in the lumen of 

 the intestine. 



Nematodes in the Physiological Interior of the Body 



The nematodes that live in the physiological interior of the 

 liody are exemplified by Dirofilaria, Spirocerca and intra-mueo- 

 sal Strongyloides. In a recent study, Hsii (1938a) was led to 

 believe that Dirofilaria immitis feeds exclusively on red and 

 white blood cells. In the ease of Diplotrinena triciispis, Hsii 

 (1938b), after studying the intestinal contents of this parasite 

 of the crow, concluded that the worms ' food consisted of the 

 inflammatory exudate in the thoracic cavity. While there was 

 evidence of blood being ingested, Hsii believed that it is not 

 taken normally. As the adult Tt'uchereria bancrofti normally 

 lives in lymph vessels and nodes, it doubtless normally feeds 

 upon lymphocytes and other constitutents of lymph. When 

 such encapsulation as shown by Faust (1939) occurs, the en- 

 capsulated worm dies, apparently from lack of food. 



In a further study of the food of nematodes, Hsii (1938a) 

 concluded that Spirocerca lupi feeds on inflammatory cells that 

 Iiass through the nodule walls. 



Observations on the food of another nematode of this group, 

 Strongyloides stercoralis, were recorded by Askanazy (1900) 

 who concluded that the mother worms in the intestinal mucosa 

 fed on chyle; he found no indication that they take blood. 

 Faust (193.5), studying Strongyloides in the mucosa of the 

 jejunum, found evidence of lytic action by the female worms, 

 particularly around the head of the worm where disintegration 

 of the tissue was observed. Considering the facts that the adult 

 females spend much of their time in the intestinal mucosa and 



352 



