PROCEEDINGS OF THE SOCIETY. 1003 



air, the paper was supplied from a revolving drum, and the air to be 

 examined was directed upon it by an aspirator. If rain water 

 was to be examined the paper was shaped as a coil, and the water 

 allowed to drop slowly upon it. He had, however, suggested to 

 Dr. Miquel that collodion films should be used instead of paper, on 

 account of the greater transparency and absence of structure. 



The President thought that this opened up a new method of 

 inquiry which would be likely, if properly used, to lead to some very 

 valuable results. 



Mr. Crisp exhibited and described Lord S. G. Osborne's Diatome- 

 scope (see p. 961), drawing attention to the fact that the lower lens 

 was mounted excentrically in relation to the upper lens, which Lord 

 S. G. Osborne regarded as an essential feature in the construction. 



The Rev. Metcalfe Gray's Ether Freezing Microtome was ex- 

 hibited and described (supra, p. 981). 



Mr. H. G. A. Wright's letter was read as follows, accompaning a 

 slide of the proboscis of the blow-fly : — 



" The enclosed slide was shown at the last meeting of the Micro- 

 scopical section of the Royal Society of N. S. Wales, and was 

 of much interest to the members present. 



It consists of the lobes of the proboscis of the blow-fly, 

 mounted without pressure, in a solution of biniodide of mercury in 

 one of iodide of potassium (both saturated solutions), and was pre- 

 pared by my friend Mr. Henry Sharp, of Adelong, N. S. Wales. It 

 shows details of the structure of the pseudo-tracheae, which I have not 

 seen hitherto described. The drawing (taken with the camera lucida 

 by Mr. Sayer) show^s the beautiful leaf-like processes of the endoderm, 

 which pass through the forked openings in the chitinous rings of 

 the pseudo-tracheae, and point out a use for that forked arrangement, 

 which all balsam mounts show so clearly. 



These processes are not alluded to in Mr. B. T. Lowne's admir- 

 able monograph on the ' Anatomy and Physiology of the Blow-fly.' 



Mr. Sharp, writing to me lately, says, ' I have several probosces 

 of blow-flies mounted in balsam, with and without pressure, but there 

 is nothing to be seen of the membrane in any of them ; I can just see 

 it in a glycerine mount, now that I know what to look for ; but the 

 glycerine docs not make it visible like the mercury solution.' 



The amplification of 1000 diameters was obtained with a Tolles 

 homogeneous-immersion 1/10 N.A. 1-33, and a Tolles 1-in. solid 

 orthoscopic eye-piece, both of the higliest excellence. Direct illu- 

 mination was used by means of Powell and Lealand's acliromatic 

 condenser." 



The President said that those who looked at the drawing could not 

 fail to be struck with it, and it would probably occur to them tliat if 

 such details could be brought out Ity the use of biniodide of mercury 

 and iodide of potassium, it deserved to be tried as a medium not only 

 for diatoms, as hitherto, but for other objects. 



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