Transmission 11 



met with in the course of his dissections. With five exceptions 

 these had ak'eady been described, in less detail, by Sonsino in 1895. 

 It is noteworthy that seven of the forms described by Sonsino do not 

 appear to have been found by Looss. The molluscs from which 

 the larval forms were obtained belonged to the following species : 

 Vivipara unicolor, Cleopatra cyclostomoides, Cleopatra buli- 

 moides, Physa alexandrina, Physa micropleura, Melania tuber- 

 culata, Limnaea natalensis, and Corbicula Caillaudi, all of which 

 had already been examined by Sonsino. A short time after the 

 issue of this paper, Dr. Looss received an appointment on the staff 

 of the School of Medicine in Cairo. His next contribution to the 

 Bilharzia question was published in 1905, as a paper [294] on the 

 " Histoire Naturelle de la bilharzia," read before the "Premier 

 Congres egyptien de medicine " : — 



"Des experiences . . . faites par Cobbold, en Angleterre. 

 par Lortet, en France, et par moi, en Egypte, eurent, sans excep- 

 tion, le meme resultat negatif. J'avais simultanement examine 

 des centaines d'exemplaires des differentes especes de mollusques 

 egyptiens recueillis dans des endroits ou la bilharziose m'avait ete 

 rapportee comme etant tres commune. S'il y avait une cercaire 

 de la bilharzia correspondant a celle des autres distomes, j'aurais 

 dii la trouver, mais je ne decouvris rien de semblable. J'ai finale- 

 ment observe au microscope la conduite des embryons de la 

 bilharzia en presence des mollusques sus-mentionnes ou de frag- 

 ments de leurs corps : or tandis que les embryons d'autres distomes 

 qui se developpent en realite dans des molhisques, sont attires 

 meme par des debris encore vivants du corps de ceux-ci et 

 s'efforcent d'y penetrer, les embryons de la bilharzia, eux, ne 

 pretaient pas la moindre attention aux mollusque que je leur avals 

 presentes." 



" Toutes les observations mentionnees et d'autres encore, 

 tendaient done a etablir que les mollusques ne peuvent pas jouer 

 un role dans le developpement de la bilharzia." 



In a polemical article, "What is Scliistosomum mansoni.^" in 

 the Annals of Tropical Medicine and Parasitology for 1908, Looss 

 [295] again asserts : — 



" All attempts made by former authors to discover an inter- 

 mediary host in whicli this development is gone through have 

 failed, and so have my own efforts. I have examined hundreds 

 of specimens of all the molluscs common in the Nile Valley with- 

 out finding any spoiocyst which might have been brought mto 

 relation with the Bilharzia worms. 1 have placed quantities of 



