190 PROCEEDINGS OP THE SOCIETY. 



Mr. G. F. Dowdeswell's paper ' On the Appearances wMch some 

 Micro-organisms present under different conditions, as exemplified in 

 the Microbe of Chicken Cholera,' was read (supra, p. 32). 



The President said that they were greatly indebted to the author 

 of this valuable contribution to a subject of such admitted importance. 

 He entirely agreed with the observations it contained as to the 

 deceptiveness which many of the processes of staining and preparation 

 produced. No doubt they had their special value, and it would be 

 quite true to say that a great deal was to be learnt by the employ- 

 ment of such means when they were regarded as processes ancilliary 

 to the object of the inquiry, and were used as means to an end. But 

 to regard such methods as producing results which they could after- 

 wards rely upon, was, he thought, only to place confidence in that 

 which further experience would be unlikely to sustain. The drying 

 of the object, and the staining it, in most cases so entirely changed 

 it, that too much stress could not be laid upon the protest now made, 

 for he had found that some of the organisms which he had examined 

 in the living state, had altered so much during the process of treat- 

 ment by reagents, that it would have been impossible to identify 

 them as the same. It was only in proportion as they worked with 

 the living, or at least unaltered specimens, that they would be able to 

 reach conclusions likely to advance their knowledge of what was true 

 concerning them. He was glad to find his own experiences so entirely 

 confirmed by an observer who had made these more recent observa- 

 tions. 



Dr. Maddox called attention to the death of Dr. John C. Draper, 

 of New York, who had for many years devoted himself largely to the 

 study of blood-corpuscles, and to photographing them. 



Mr. J. W. Stephenson's paper "On 'Central' Light in Kesolution" 

 was read, the object of the paper being to call attention to the mis- 

 understanding that had arisen by the alleged resolution oi AmpMpleura 

 by central light, that is with half the real aperture (supra, p. 37). 



Mr. E, M. Nelson thought the paper touched upon a very impor- 

 tant matter, with regard to the questions of central and oblique light. 

 When Prof. Abbe's theory came out, it a as said that every micro- 

 scopist should have an apparatus to examine the diffraction spectra, 

 on which alone the power of resolution depended. This appeared to 

 him to be manifestly wrong, because it was quite certain that the best 

 resolution of P. formosum was obtained when the whole field of the 

 Microscope was full of light, and no diffraction spectra were visible. 

 This theoretically reduced the power of resolution, but as a fact, the 

 resolution itself was enormously increased. He was about to read a 

 paper bearing upon the subject, at another place, dealing with an 

 object which was immensely more minute than most of the so-called 

 tests; this could be seen only with central illumination, and he 

 thought the ability to resolve this vp^as of more value than the re- 

 solution of lines. What he referred to was a small spicule extending 

 across one of the spaces between the lines on the diatom ; taking the 



