136 PEOCEEDINGS OF THE SOCIETY. 



egg. Several new and interesting species were described and figured, 

 and exhibited under Microscopes. 



The President said he was very glad that Mr. Michael did not 

 form a new species from a single specimen. The history of the 

 death of the parent insect before the escape of the ova was, he 

 thought, very anomalous in nature; indeed, he did not remember 

 anything at all like it. Many of the Lepidoptera died very soon after 

 the eggs were laid, but he knew of no case in which this remarkable 

 circumstance had been observed. 



Mr. Stewart did not remember any in which the eggs were retained 

 in the body of the dead mother, but in the case of the Coccus there 

 was something, perhaps, a little like it, the mother dying immediately 

 after the deposition of the eggs, and forming a sort of roof over 

 them with her dead body, which served to protect them during the 

 winter. 



Mr. J. W. Stephenson exhibited Pleurosigma formosum mounted 

 in a solution of biniodide of mercury and iodide of potassium, a 

 mounting fluid which, with the exception of solution of phosphorus, 

 had a higher refractive index than anything known to him. It had 

 been used by Mr. Browning for prisms, and had an index of 1 • 68. 

 The index of bisulphide gf carbon was 1 • 624, of monobromide of 

 naphthaline, 1*658, and of sulphur, 1*662, so that the biniodide of 

 mercury was *056 higher than bisulphide of carbon. Mr. Browning 

 found that the best means of sealing it was by using white wax. He 

 had brought some of it to the meeting as a sample. Being an aqueous 

 fluid appeared to be a great advantage, and it could be used of any 

 strength from 1 ' 33 to 1 * 68. 



The President said he had had his eyes opened to the value of 

 this solution as a highly refractive medium, but had been disappointed 

 by being told that it was only useful for purposes of spectrum analysis, 

 in consequence of the great effect which it had on the red rays. 



Mr. Stephenson did not know how far its great dispersive power 

 would be prejudicial, but he had tried it for mounting, and found that 

 it did very well for diatoms. 



Mr. Symons read a paper on " A Hot or Cold Stage for the 

 Microscope " (see p. 21), the details of which were drawn upon the 

 board and the ajjparatus itself exhibited. 



The President inquired if Mr. Symons had used this stage for 

 observing the motion of the white blood-corpuscles. He also 

 suggested that the brass would be better if it came rather more flush 

 with the plate. 



Mr. Symons had not examined corpuscles with the stage, having 

 hitherto only applied it to ascertaining the melting-points of various 

 substances. He thought there would be no difiiculty in using high 

 powers with it, as the objective could be brought into actual contact 

 with the glass if desired, the only thing between the plate and the 

 objective being the thin glass. 



