126 THE EFFECTS OF PARASITES ON THEIR HOSTS. 



much the same in the case of the Tcenice, and even of Twnia sayinata, 

 which throws off, let us say, eleven proglottides daily, with an 

 average weight of 1*5 grms., and thus loses in the course of the year 

 about 550 grms. of organic matter. If the number of parasites be 

 greater, the association is of course more unfavourable. A female 

 thread-worm, for example, produces, as we saw before, 42 grms. of egg- 

 substance yearly ; and taking into account what it requires for meta- 

 bolism, must deprive its host during this time of at least 100 grms. 

 Thus if, as sometimes occurs, there were 100 of them (there have been 

 cases in which 1000 have been found at the same time in the in- 

 testine), they would cause a loss of 833 grms. monthly, which, under 

 some circumstances, and especially in childhood, must have a very 

 appreciable effect. Similarly, the 100,000 specimens of EhaMitis 

 stercoralis (1 mm. long, 04 mm. in diameter) which are often 

 evacuated daily by patients suffering from Cochin-China diarrhoea, 

 represent by their mass alone without 1 taking into account material 

 used in metabolism a weight of about 200 grms. And if it be con- 

 sidered further that the number of the evacuated worms may increase 

 tenfold, it becomes easy to understand how a severe marasmus may 

 ensue, even after a short illness. 



I do not, however, cite these instances in support of the view 

 that the disturbances of the nutritive functions, and their manifold 

 external consequences, which the physicians were so willing to in- 

 terpret as symptoms of helminthiasis, are always to be regarded as 

 the direct consequences of the amount of nutritive material ab- 

 stracted by parasites. Even if it be certain that the disease is con- 

 nected with parasites, it is quite possible that the relation between 

 disease and parasite is of an indirect nature, and brought about by 

 the state of the infected organ. 2 Further, the continuance of any 

 disease, however slight and partial at first, will affect the general con- 

 ditions of the nutritive organs. 



Nor is the nature of the materials which serve as nourishment to 

 the parasites an unimportant factor in considering the effects of the 

 association. Thus a blood-sucking parasite, cceteris paribus, causes a 

 greater loss than one which feeds on epithelial cells. To this is due 



1 [As above mentioned (p. 46), these Rhabditidae are the offspring of Ancjuttlula 

 intestinalis, which had been met with in the intestine by earlier observers, but whose 

 genetic relation had remained unrecognised. Grassi and Perona have recently reported 

 that they have found AnguilluLa intestinalis in patients suffering from catarrhal gastro- 

 enteritis in Milan (Archivio scienze medic., t. iii., No. 4, 1879). R. L.] 



2 A very good example is afforded by the Trichina?. In their wandering into the 

 muscular tissue they not only destroy fibres, but, by paralyzing the muscles used in masti- 

 cation and swallowing, they affect the introduction of nutriment to such a degree that 

 within a very short time the patient experiences considerable atrophy. 



