398 



and so, while he might say he believed in the theory, he would also say that 

 he did not believe in its application. Professor Abbe said, with regard to 

 Amphipleura pellucida, that you could not tell anything at all about the 

 structure, consequently one was always being met by " what Professor Abbe 

 says about it." In the Royal Microscopical Society's Journal they were 

 shown a number of effects which took place in the case of Pleurosigma 

 angulatum, but with regard to these he could only say that what was true 

 was not new, and what was new was not true ; in fact, the only one that 

 was true was the figure shown by Mr. Wenham, and he was sure that when 

 they looked at one side of the valve they got the same structure through- 

 out, but on the other side they got effects which were due to a grating, 

 which was in fact simply adding another structure. 



The President, with regard to the remarks of Mr. Nelson, said that he 

 was quite clear on the point that they could not have diffraction images 

 irregularly, and that if irregular forms of structure were seen in such things 

 as spicule, and sections or fractures of diatoms or other things, those 

 appearances could not be due to diffraction. With regard to belief or dis- 

 belief in diffraction theories, he did not know how that could affect results ; 

 the important thing was rather a question of belief or disbelief in the 

 instrument they worked with. They could not, of course, see anything that 

 the instrument did not show, but the point was whether, under certain con- 

 ditions, they could from what they saw determine the nature of the structure. 



The Chairman said that after the way in which the paper had been 

 received it was hardly necessary for him to ask them for a vote of thanks 

 to the President for what had certainly been one of the clearest and most 

 practical demonstrations on the subject to which he had yet listened, and it 

 would form a most important addition to the information which had been 

 written on the subject. The day had not yet come when the microscope 

 could be pronounced perfect, and in view of this an explanation such as they 

 had listened to that evening could not fail to be of the highest importance, 

 and had evidently been received by the members with extreme appreciation. 



A vote of thanks to the President was unanimously carried. 



Announcements of meetings, etc., for the ensuing month were then made 

 and the proceedings terminated with the usual Conversazione, the following 

 objects being exhibited: — 



Choano fiagellata, etc Mr. F. W. Andrew. 



Section of earthworm, Lumbricus ruhellus ... Mr. H. E. Freeman. 



Leaf of Plumbago capensis alba Mr. G. E. Mainland. 



Attendance — Members, 45 ; Visitors, 2. 



February 8th, 1889. — Conversational Meeting. 



The following objects were exhibited : — 



Larva of Corelhra plumicornis Mr. F. W. Andrew. 



Nostoc, sp Mr. G. E. Mainland. 



BiddulpJiia reticulata Mr. H. Morland. 



Mastax of Hydatina senta Mr. J. Spencer. 



