420 



ful place, with many rare birds and swarms of vipers (!) in the 

 garden. 



Replying to a question by Dr. Spitta, the President said all 

 the pathogenic species of Trypanosoma were much smaller and 

 very distinct in structure, and all the evidence tended to show 

 that the forms found in fish would nob live in the blood of 

 mammals. These parasites, especially the harmless forms, are 

 quite specific to the host. The trypanosome of the rat died at 

 once if transferred to the mouse, and even in the guinea-pig it 

 would only live a little while, and would not multiply. Lethal 

 forms, however, flourish in many different hosts. The study of 

 trypanosomes was of great importance, both zoologically and 

 economically. 



On the proposal of Mr. D. Bryce, seconded by Mr. F. P. Smith, 

 a very hearty vote of thanks was accorded to the President for 

 his remarks. 



Mr. T. A. O'Donohoe read a note, illustrated by a number of 

 excellent lantern slides, on " The Photographic Evolution of the 

 Fine Structure of the Podura Scale." He said, in the 

 Illustrated Annual of Microscopy for 1898 there are four photo- 

 graphs of the Podura scale by two of the ablest photomicro- 

 graphers living, who were well equipped with the very best 

 apochromatic objectives and condensers. It may therefore be 

 fairly assumed that these photographs represent all that was 

 then known of the Podura scale. The one (x 1000) by 

 Dr. Spitta shows a constricted head and white streak to the 

 "exclamation mark," and that is all. The spaces between the 

 " exclamation marks " show no trace whatever of structure. 

 Mr. Gifford's three photographs at x 1350, x 1944, and x 4860 

 respectively do, here and there, show some fine vertical lines 

 between the marks ; but they are so faint that the speaker 

 noticed them only when, some years later, he was comparing 

 these photographs with his own, in one of which (then thrown on 

 the screen), the fine vertical lines emanating from the heads of 

 the " exclamation marks " were well brought out. In 1905, at 

 Mr. Nelson's suggestion, he produced a photograph showing the 

 membrane of the scale, and, later, two others, the second at 



