110(3 PROCEEDINGS OF THE SOCIETY. 



doubted the existence of a flagellum, but although it was a thing 

 very difficult to be seen, this was not tho first time it had been 

 photographed. Koch had been able to do this after a process of 

 staining, for which ho recommended the use of a watery solution of 

 logwood and subsequent treatment with chromic acid, but he had rather 

 given up the attempt to photograph specimens unless he could get 

 them stained brown. This, however, he (Dr. Crookshank) had not 

 found to be essential when using isochromatic plates ; the specimen 

 shown had been stained with gentian violet, and it would be found on 

 examination that the flagella were very distinctly seen. lie would also 

 hand round for inspection another negative, to show that it was possiblo 

 to get very good results without staining brown ; the specimen being 

 Spirochseta, from sewage-contaminated water, for which he was 

 indebted to Mr. Cheshire. He had also mentioned in the paper to 

 which he referred that in reproducing the photographs the colour given 

 to the prints was rather objectionable, and he had suggested to the 

 Autotype Company that they should try to use some other colouring 

 matter for the purpose, but it had been found very difficult to carry 

 out this idea at present. The micro-organisms exhibited had been 

 enlarged 25,000 times. 



The President said that to him it was of exceeding interest to 

 examine the photographs which had been brought for their inspection 

 by Dr. Crookshank, seeing that they depicted objects which for years 

 he had been drawing and studying. Koch had for a long time failed 

 to detect the flagella with his eye, but when he photographed the 

 object the flagella appeared. Now that they were able to obtain 

 photographs in the manner which Dr. Crookshank had so successfully 

 adopted they would be able to see for themselves all the minute 

 details which had been described. He felt it was a great gain to 

 have photo-micrography so readily and easily at disposal, and 

 personally he felt very much obliged to Dr. Crookshank for bringing 

 the matter before them. 



Mr. Crisp inquired if Dr. Crookshank had tried to obtain photo- 

 graphs by means of the new objectives. One of the greatest 

 advantages claimed for them was their use in photo-micrography, 

 apart from the advantage of being able to obtain the same power with 

 an 1/8 in. objective as had been obtained with the very much higher 

 powers used in producing the negatives exhibited. 



Dr. Crookshank said he had not yet had any opportunity of trying 

 either the objectives or the projection eye-pieces. His negatives were 

 taken with a 1/25 in., by Powell and Lealand. 



Mr. C. D. Sherborn and Mr. F. Chapman's paper " On some 

 Microzoa from the London Clay, exposed in the Drainage Works, 

 Piccadilly, in 1885," was taken as read, as it had been printed during 

 the recess (ante, p. 737). 



Dr. Anthony's note on the observation of opaque or quasi-opaque 

 objects in the Microscope, was also taken as read, having been 

 printed during the recess (ante, p. 857). 



