82 THE MICROSCOPE. 



Dr. George Tayler Robinson, of this city, recently graduating, 

 and a son of Heber Robinson, Esq., was introduced, a synopsis of 

 his remarks upon "Photography in the Eye" following: 



The subject was really part of the wonderful properties of 

 that little known compound, visual purple. The doctor, after 

 defining the compound as an organic photo-chemical substance 

 situated in the rods of the retina, described the effect which light 

 has upon it. It was only found in the retina, he stated, during 

 total darkness, and that when brought into the presence of light 

 underwent a change from purple to orange, then became gradually 

 diluted to a yellow color, and finally vanished, leaving the retina of 

 a white color. These changes, he added, had been described by 

 Kuhne respectively as visual purple, visual orange and visual 

 white. The lecturer then gave the process for obtaining the visual 

 purple, and explained by various illustrations how the objects are 

 photographed on the retina. He had been able to imprint upon 

 the retina such objects as rectangular figures, crosses, etc. He 

 then reviewed his numerous experiments which were instituted 

 with the view of ascertaining the functions of the visual purple, 

 and stated that his researches had led him to believe that the com- 

 pound was a modifier of the intensity of light. He explained how 

 he had found this property of the purple to exist. He cited cases 

 in the lower animals which seemed to indicate that this was the 

 actual function of the compound. He then concluded by showing 

 how the knowledge of this photo-chemical substance might be of 

 value to the medical jurist in determining the character of the 

 surroundings in the case of the death of an individual. 



(;R1FFITH MICROSCOPIC.A.L CLUB OF D.ANVILLE, ILL. 



The regular monthly meeting of the Griffith Club, of Danville, 

 111., was held on Friday evening, May 19, at the residence of 

 the President, the Rev. F. W. Taylor, who occupied the chair. 



When the business brought before the Club was finished, the 

 subject for the evening was brought up — "Double Staining of Vege- 

 table Tissues." 



Dr. Converse, to whom a paper on that subject had been as- 

 signed, failing to appear, the President was called upon for his ex- 



