Tra)is))iission 17 



tered to various species of monkey, to sheep, I'cabbits, guinea-pif^s, 

 and rats. Subcutaneous injection, applications to the shaven skin, 

 attempts to infect by bathing and by the mouth, were without 

 result in every case. 



A number of experiments have also been made by FilUeborn, 

 by certain of Dr. Looss's colleagues and by the author, but lacking 

 success, these have not been put on record. 



These repeated failures to obtain experimental verification of 

 his theory are explained away by Looss [300] with the statement 

 that man is the only known host of Bilharzia hcematohia. 



It is right to add that a number of authorities, 



Dissentients, notably Blanchard and Manson, have consistently 



withheld their assent to the Looss hypothesis. In 



"Maladies parasitaires" Blanchard [37] wrote in December, 1895 : — 



"II est hors de doute que I'embryon eclofc normalement dans 

 I'eau et qu'il penetre dans le corps d'un animal aquatique, pour 

 y accomplir sa phase larvaire. Neanmoins on n'a pu jusqu'ici 

 decouvrir en quoi consistaient ses metamorphoses et chez quel bote 

 elles s'accomplissaient. Lortet et Vailleton . . . ont cherche 

 I'embryon et la Cercaire dans les eaux des rivieres et des mares 

 d'Egypte au moyen de peches au filet fin, sans pouvoir le rencontrer 

 jamais. lis ont dresse la liste des animaux qui vivent dans ces 

 eaux et les ont examines avec le plus grand soin, sans jamais y 

 trouver aucun parasite qui soit imputable a I'une des phases de 

 revolution de la Bilharzie. Le mode de developpement et de 

 propagation de ce Trematode reste done encore entoure d'un 

 profund mystere." 



In 1905 Sir Patrick Manson [329J, in his "Lane Lectures on 

 Tropical Diseases" (p. 50), expressed the opinion that Bilharzia is 

 " another illustration of the conveyance of a disease germ through 

 water and probably by a fresh -water intermediary," while in the 

 latest (1914) edition of his text-book on "Tropical Diseases" he 

 writes : " Analogy suggests that the miracidium passes into the body 

 of some fresh-water mollusc, crustacean, or larval arthropod, there 

 to undergo the developmental changes in the redia and possibly the 

 cercaria stages usually exhibited by the trematodes. Later, it may 

 become encysted, and then, either free or still in the body of the 

 intermediate host, gain access to man by penetrating the skin or 

 through the stomach, and so pass to the veins of the portal 

 system." 



" Looss has expressed the opinion that, unlike other trematodes, 







