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tilled water, and there was no mycelium in that after several years. He 

 found, however, that it formed on the surface of a saturated solution of 

 common salt. 



Dr. Matthews said that at the time he alluded to he did not use distilled 

 water, but any that was l'eady to hand. 



Mr. Sigsworth said that camphor water had been found to preserve even 

 a solution of citric acid. 



Mr. Spencer thought that distilled water was not always to be relied upon, 

 for Prof. Tyndall stated in his book on " Moving Matter in the Air," that he 

 had found Bacteria in nearly all the distilled waters supplied to him by the 

 chemists. 



Mr. Hardy described a method of illuminating crystals and similar objects 

 by coloured light, termed by him the " Chromatoscope." 



Mr. Hainworth inquired if he correctly understood Mr. Hardy to say that 

 all crystals to be viewed in this way must be mounted dry. 



Mr. Hardy said this was so. It would not do to mount them in 

 balsam. 



Mr. Ingpen exhibited a series of diagrams which had been drawn for him 

 by Mr. W. T. Suffolk to illustrate Professor Abbe's theory of the vision of 

 minute objects by their diffraction spectra. They were very beautifully 

 and correctly drawn in their proper proportions, as seen in the micro- 

 scope. 



Mr. Michael made some interesting remarks with reference to a slide which 

 he exhibited in the room — one of the Chalcididae — a class of insects which 

 he described as being very remarkable on account of the extraordinary 

 variations which existed amongst them, and for the wouderful persistence 

 of their predatory instincts. Sketches on the black board were made in 

 illustration of the curious development of the antennas. 



Dr. Matthews inquired if Mr. Michael had any suspicion as to the special 

 function of this very curious organ. 



Mr. Michael said he was scarcely able to say what its special use might 

 be. The auditory organs were usually supposed to be in the antennas, and 

 probably were so, though perhaps nearer the base. He should suppose 

 that this was more of a tactile organ, its development rendering it of use 

 to the creature over a comparatively large area; the constant rapid play 

 of the antennas certainly gave the impression that they were tactile 

 organs, and that probably they might be necessary to enable the 

 insects to appreciate the vibrations by means of which they tracked their 

 prey. 



Mr. Ingpen said he had brought for exhibition a slide of Volvox, mounted 

 in a dilute solution of iodide of potassium, which seemed to promise so well 

 for the preservation of Yolvox and Desmids, and such like things, that he 

 should like some one else to try it. He could not tell the exact strength 

 of the solution, but it was certainly weak ; he believed it was about 5 grains 

 to the ounce when mixed with the water containing the organisms, 

 though it might be well to vary the strength according to the condition of 

 the algse to be treated. The slide which he had brought was of Volvox, in 



