The Dawn of Microscopical Discovery. By C. Singer. 327 



the organism. . Bonomo and Cestoni attained to a correct idea of the 

 nature of the Sarcoptes, its life-history and its role in the disease. 

 Beyond this point we need not trace in detail the history of our 

 knowledge of the organism. 



JS 



l d 



Q 



JPig. 40. — Sarcoptes scabiei and their eggs, from the " Osservazioni . 

 intoruo ai pellicelli" of Bonomo and Cestoni, 1687.. 



Gradually among scientific writer the Sarcoptes became accepted 

 as the cause of the itch, and although doctors waited for another- 

 hundred years before they were convinced by their colleague 

 Wichman (1740-1802),* we can yet. say that by Bonomo and 



Pig. 41.— Dorsal and ventral aspects of Sarcoptes scabiei, 

 from Fuerstenberg. 



Cestoni the organic cause of an infectious disease was for the first 

 time scientifically demonstrated. Those who would learn of the 

 subsequent progress of our knowledge of the subject may be 

 referred, with the writer's sympathy, to the monumental work of 



* Johann Ernst Wichmann, " Aetiologie der Krittze," Hanover, 1786. 



