.'>4 tricliuris iiit'i'c-tod patients. In support of tlie view that 

 these nematodes may feed on lilood were the tindinjjs of Li 

 (1933e) and Chitwood and C'hitwood (My^l) that the adult Tri- 

 chtiria bears a stylet capable of insertion suflieient for drawing 

 blood. Chitwood and Chitwood (ISU?") showed that the anterior 

 muscular [lart of the trieluiroid esophaKUs possesses uiuselcs 

 capable of the dilation necessary for .sucking. Moreover, they 

 found by serial sections a large number of red coipuscles in Ihc 

 esophageal lumen of Trichi(ri.i. While Smiruov (1936), after 

 a comprehensive study of the literature and of serial sections 

 of worms, concluded that there was no convincing evidence 

 that trichurids feed on blood, the fact remains that Whipple 

 (IIHH)) and Garin (1913) reported the occurrence of hemolytic 

 enzymes in Trichiiris. From the various studies made it ap- 

 pears that trichurids secure their food from the intestinal 

 mucosa and that it may consist of liquified mnco.sal tissue and 

 Idood elements. 



Studies on the food of Tricliim Uti xpiralix were made by 

 Heller (1933) who introduced encysted trichina larvae enclosed 

 in collodion sacs into the snuiU intestines of cats and rats. 

 While the meat around the larvae was digested in to 8 hours, 

 they made no growth in 1 to 3 days. Trichiiiella larvae en- 

 closed in fine silk bags and thus kept away from the intestinal 

 mucosa likewise did not develop. That these nearly adult 

 trichinae do not feed on intestinal contents seems likely also 

 from other tests by Heller who fed India ink along with meat 

 containing encysted larvae, but failed to find any ink in the 

 worms' intestines. Sections of intestinal tissue made after 

 the encysted trichinae were fed showed that the freed larvae 

 penetrated the intestinal mucosa, where the maturing trichinae 

 doubtless secure their food. 



Following the work of Heller, McCoy (1934) injected sterile 

 TrichineUa larvae from digested rat muscle into the amniotic 

 sac of chick embryos li to 1.5 days old. Definite growth of the 

 maturing larvae occurred in only about 1 or 2 percent of the 

 trichinae. A single female developed to sexual maturity. Bet 

 ter success was attained in a second series of experiments in 

 which the sterile larvae were injected into the amniotic sacs of 

 rat embryos on approximately the 14th day of gestation. In 

 2 to ,■) days, practically all worms were developing at nearly 

 the normal rate and on the fifth day, numerous female trichinae 

 were found with embryos developing in their uteri. These re 

 suits give further evidence that TrichineUa normally feeds upon 

 host body fluids secured from the mucous membrane. Moreovei', 

 van Someren (1939) reported a functional buccal stylet in T. 

 spiralis and indicated that it is used to lacerate the host tissue 

 and release tissue fluids. From the examination of living 

 specimens immediately after recovery, van Someren believed 

 that the food, which is in a fluid state when ingested, consists 

 of tissue fluids, cell contents, or perhaps predigested tissue acted 

 on by a tissue lysate from the anterior esophageal glands. 



Among other nematodes attached much of the time to the 

 enteric mucosa is Plnisaloptcra. Studies by Hocppli and Feng 

 (1931) showed that the mucosa about the anterior ends of these 

 attached worms was liquified or partially digested, presumably 

 from esophageal secretions from the nematodes. Studies of 

 sectioned mucosa showed definite excavation of tissue immedi- 

 ately around the anterior ends of the worms, presumably from 

 the taking of the liquified tissue as food. 



UNATTACHED NEMATODES CLOSELY ASSOCIATED 

 WITH THE MUCOSA 



Many nematodi's belonging to this grou]), while Iniving jioorly 

 developed buccal capsules, are able to puncture the mucous 

 membrane and draw blood. For example, Stadehnann (1891) 

 found blood corpuscles in the nearly nuiture Ostertagia oster- 

 tagi (Strongylu.i convolutiis) in nodules of the abomasum, and 

 Dikmans and Andrews (1933) found such stages of Ostertagia 

 circwmcincta in the mucosa and partly free in the abomasal 

 lumen of sheep. Unfortunately, however, much of the evi- 

 dence is circumstantial. Thus Ransom (1911), writing of 

 Haemonchus contortiis and Ostertagia ostertagi, stated that 

 they evidentl.v suck blood for the heavily infected liosts arc 

 anaemic. Other writers simply state that they suck blood. 

 Veglia's (191(5) observations on living worms demonstrated 

 that the oral lancet made definite cutting movements. Fallis 

 (1938) placed Nematodirus among the blood suckers on the 

 basis of a spectroscopical analysis of the body fluid which 

 showed the absorption bands for oxyhaemoglobin. In the same 

 year, Davey (1938), who studied the food of nematodes of the 

 alimentary tract of sheep, questioned the spectroscopic demon 

 stration of haemoglobin in nematodes as evidence of their being 

 blood suckers. He found that haemoglobin was present in tissues 

 other than the alimentary canal of Nematotlinis spathigrr and 

 that its absorption bands had different positions from those in 

 the blood of their hosts. These facts, together with his finding 

 of haemoglobin in species of Trichostrongylidae long after 

 any haemoglobin from the host would have decomposed, proved 



Ihat these nematodes could synthesize haemoglobin. Davey 's 

 (1938) culture tests with serum, blood digests, and defibrinated 

 blood as food for Ostertagia, Cooperia, Nematodirus and Tri- 

 vliostrongi/lus were unsuccessful, as were also those on abo- 

 masum fluid for Ostertagia circumciiicta. These negative re- 

 sults led him to the conclusion that these nematodes with rudi- 

 mentary buccal capsules pjobably feed on tissue elements at oi 

 ill the mucosa. 



Other evidence of intinuite association of trichostrongyles 

 with the mucosa of the alimentary tract is available from rab- 

 bit neumtodes. Alicata (1932) experimentally infected rabbits 

 with Olxliscoides ciinieiili by feeding infective larvae. Ex 

 amination about 2 months later showed nematodes free on the 

 mucous membrane of the stomach or under the membrane and 

 into the snbmncosa. That such trichostrongyles feed from the 

 enteric wall was the opinioTi of Wetzel and Enigk (1937) who, 

 on infecting raljbits with (irapliidiiim strigosum, found tlie 

 stonuich mucosa bloody. Enigk (1938) examined the intestinal 

 contents of several sexually mature G. strigosum and found a 

 colorless viscous mass containing nuclear remnants apparently 

 from white blood cells, granules and bacteria. Other tests such 

 as feeding the rabbits pulverized chaicoal. trypan blue and car 

 mine resulted in these substances being ingested by the nenm 

 todes. Also, injecting the hosts intravenously with trypan blue 

 for several days resulted in the worms taking up several blue 

 colored particles presumably desquamated mucosa cells. Enigk 

 concluded that G. strigosiim's food consists of gastric mucosa, 

 gastric juice and stonnxch contents. 



Other unattached nematodes closely associated with the mn 

 cosa include lungworms which inhabit the bronchi and bron 

 chioles. Hung (1920) studying swine lungs infected with adult 

 Metastrongylus elongatus frequently found eosinophiles and red 

 blood corpuscles in the worms' intestines. The findings of Por- 

 ter (1930), who made similar studies, indicated that the mate- 

 rial in the worms ' intestines consisted of elements identical 

 with those found in the exudate surrounding the nematodes. 

 In cross sections of the worms. Porter recognized large uum 

 bers of eosinophilic and neutrophilic polymorphonuclear leuco- 

 cytes, lymphocytes and desquamated epithelial cells. Erythro- 

 cytes w^ere seen in some instances. These and some of the leuco- 

 cytes and epithelial cells appeared to have been digested in part 

 by the worms. 



From the findings of the investigators cited, the food of 

 many of the unattached sti'ongyles appears to consist mainly 

 of substances derived from the mucosa, namely, leucocytes, 

 erythrocytes, lymphocytes, plasma, exudates and desquamated 

 mucosa cells, but also of some extra-mucosal material such as 

 stomach contents. 



UNATTACHED NEMATODES NOT CLOSELY ASSOCI- 

 ATED WITH THE MUCOSA 



Chief among the parasitic nematodes not closely associated 

 with the intestinal mucosa are members of the Oxyuroidea and 

 Asearidoidea. Among the early observations of the food of 

 such nematodes were those of Leuckart (1876) who found that 

 the intestine of Enterutiius vermicidaris usually contained yel- 

 low fluid which on microscopical examination proved to br 

 identical with the liquid host feces. Similar observations wi'rr 

 made by Leuckart on Oxyuris equi whose intestinal contents 

 contained small particles of vegetable material identical with 

 the contents of the horse intestine. 



Early in the present century, Weinberg (1907) examined the 

 intestines of many Ascaris specimens but could not find red 

 blood corpuscles in them and expressed the opinion that the 

 horse Parascaris feeds on the contents of tlie host intestine. 



To ascertain whether Ascaris feeds upon intestinal contents, 

 Vogel, cited by Hoeppli (1927), fed powdered animal charcoal 

 to a human patient infected with Ascaris. The results of the 

 first test were negative, but in a second test carried out simi- 

 larly, numerous charcoal particles w-ere found in the intestine 

 of the worm. On the other hand, a number of early workers 

 held to the view that the ascarids are blood suckers. This view 

 was derived, in part, from microscopical and chemical examina- 

 tions which showed evidence of blood in the intestines of 

 Ascaris and related forms. For example, Mueller (1929), on 

 studying specimens of Anisakis simplex from the sperm whale 

 stated that the intestine, in all cases, contained blood in con- 

 siderable quantities with occasional fragments of muscle and 

 other tis.sues. From the quantities of blood corpuscles pres- 

 ent, Mueller was of the opinion that the nematode had a blood- 

 sucking habit. Mueller was unable to determine the nature of 

 the intestinal contents of any other genus of the Anisakinae 

 that he studied. 



If such ascarid forms are blood suckers some specimens 

 should be found in contact with the mucosa. Hoeppli (1927) 

 reported on the examination of 350 cadavers in which large 

 numbers of ascarids were found. No evidence was available 

 to show that anv of these nematodes were attached to the mu- 



351 



