154 PROCEEDINGS OF THE SOCIETY. 



under a Microscope, of the lung of a mouse infected with a form 

 of septicgemia. 



The Chairman thought the experiments described were very im- 

 portant, from the fact of their having been conducted under such high 

 powers. Investigations of this kind required an amoimt of time and 

 a delicacy of manipulation which might well make the Society grateful 

 to any one who bestowed upon them the necessary attention. He was 

 very glad that Mr. Dowdeswell intended to continue the same line of 

 investigation, and that he had promised they should hear the results 

 of his further researches. 



Mr. Crisp exhibited (1) Martens' Ball-jointed Microscope (Vol. II. 

 (1882) p. 672); (2) Hartuack's (or Eecklinghauseu's) Demonstration 

 Microscope (Ibid., p. 97) ; and (3) the latest form of Mr. E. H. Griffith's 

 Club Microscope (^ante, p. 113). 



Mr. F. Kitton's paper on " Binocular Vision in the Study of the 

 Diatomacefe " was read. 



Mr. Beck said, that with reference to the opening remarks of the 

 author on the value of binocular over monocular vision, he could fully 

 bear out all that had been said. A valuable means of convincing 

 any one who was sceptical on the subject was to be found in a slide 

 of Aulacodiscus ; and he remembered that when his brother Eichard 

 showed this diatom to Mr. Tuffen West for the first time under the 

 binocular, that distinguished draughtsman looked at it for some time 

 in silence, and then jumping up, exclaimed, "All the drawings of 

 Diatomacese which I have done will have to be done over again." 



Dr. TVallich said he could folly confirm the statement that nothing 

 showed diatoms so well as the binocular. Indeed, from a study of 

 these objects extending over many years, he could say that it was 

 utterly impossible to see them in any other way. In one of the 

 drawings of Hydrosira, he observed that Mr. Kitton had not noted the 

 unsymmetrical formation consisting of a little dot which was gene- 

 rally surrounded by a slight ridge on one side only. It occurred in 

 Hydrosira and many of the discoidal forms, and, though often seen, 

 he had never been able yet to detect what this peculiar structure was. 

 It would be of advantage if some one would set to work to determine 

 it. It seemed to him to have something to do with the communica- 

 tion between adjacent frustules. 



Mr. Crisp said that Mr. Kitton had proved conclusively the 

 superiority of the binocular, in that he had shown the true form of 

 diatoms, which had previously been misinterpreted by most expe- 

 rienced observers after observation with the monocular. 



Dr. Wallich, in reply to Mr. Badcock, stated that in examining 

 these objects under high powers, he used the thinnest slide he could 

 find and the thinnest cover-glass. Generally he used one of Hart- 

 nack's objectives ; the only difficulty was to get the whole of the field 

 illuminated, but it was not really necessary in by far the larger 

 number of cases to use more than the central part of the field, which 

 could always be illuminated. 



