10 THE ANIMAL PARASITES OF MAN 



the effects of such poisons explain the pathology of helminthiasis 

 far more satisfactorily than the theory of reflex action. 



In a number of cases these toxic materials (leucomaines) have 

 been isolated and their effects on living organisms demonstrated 

 by actual experiments. It also appears that the absorption of 

 materials formed by the decomposition of dead helminthes may 

 likewise cause toxic effects. However, our knowledge of these con- 

 ditions is as yet in its initial stage. 1 



Nearly all the symptoms caused directly or indirectly by para- 

 sites are of such a nature that the presence of the parasites 

 cannot be diagnosed with any certainty, or only very rarely ; the 

 most that can be done is to deduce the presence of parasites by the 

 exclusion of other causes. Fortunately, however, there are sufficient 

 means by which we may confirm the diagnosis in a great many cases. 

 Such means consist not only in a minute examination of the patient 

 by palpation, percussion and local inspection, but also in the micro- 

 scopical examination of the natural secretions and excretions of the 

 body, such as sputum, nasal mucus, urine and fseces. Though such 

 examinations may entail loss of time, they are necessary in the interest 

 of the patient. It appears to me, moreover, that quackery, which has 

 gained considerable ground even in the treatment of the helminthic 

 diseases of man, can thus be considerably limited. 



Origin of Parasites. In former times, when the only correct views 

 that existed related to the origin of the higher animals, the mode 

 of procreation of the parasites as well as of other low animals 

 was ascribed to SPONTANEOUS GENERATION (generatio cequivoca), and 

 this opinion prevailed throughout the middle ages ; the writers on 

 natural science merely devoted their time to the interpretation of the 

 views of the old authors, and perpetuated the opinion of the ancients 

 on questions which even in those days could have been correctly 

 explained merely by observation. 



It was only when observations were again recommenced, and the 

 microscope was invented, that the idea of spontaneous generation 

 became limited ; not only did the microscope reveal the organs of 

 generation or their products (eggs) in numerous animals, but, Redi 

 succeeded in proving that the so-called Helcophagi (flesh maggots) are 



1 Moursson, et Schlagdenhauffen, " Nouv. reck. din. et phys. sur quelq. liquides organ.," 

 C. R. Ac., Paris, 1882, p. 791 ; Debove, " De I'intox. hydat.," Bull, et Mem. soc. m,'d. des 

 hopit., 1888 ; Linstow, v., "Ueb. d. Giftgehalt d. Helm.," Internat. Monatsschr. /. Anat. u. 

 Phys., xiii., 1896 ; Peiper, "Z. SymptomatoL derthier. Paras.," Deutsche med. Wochenschr., 

 1897, No. 40; Mingazzini, P., " Ric. sul. veleno d. elm. int.," Rass. intern, d. med. 

 modern. Ann., ii., 1901, No. 6 ; Vaullegeard, A., "Etud. exp. et crit. sur V action d. helm." 

 Bull. soc. Linn, de Normandie, 5, Ser. T. vii., 1901, p. 84, and others. 



