358 PROCEEDINGS OF THE 



The meeting closed with a hearty vote of thanks to Mr. Curwen 

 for his valuable contribution to practical microscopy. 



Since the above paper was read, certain modifications which 

 at that time were in the experimental stage have been developed. 

 The most important is the substitution of balsam for wax as a 

 sealing agent, the advantages being greater permanency and 

 the avoiding of the necessity for heating the slide. Balsam in 

 xylol has been found to be most suitable, and this is run in round 

 the cover-glass by means of a dropping rod. In this case metal 

 or celluloid spacing pieces are preferable to card, as the latter con- 

 tains air which issues as bubbles when immersed in xylol balsam. 

 The only disadvantage of the method is the fact that an object 

 once mounted cannot be readily dismounted as with the wax. 



During the present year about 800 slides have been sealed 

 with balsam and there are no failures of any sort to report. 

 The xylol balsam will harden at the edges in about a week 

 sufficiently to enable the cover-glasses to be gently cleaned and 

 the slides carried about. Gold size has also been used as a seal 

 instead of balsam, but it is not considered to be so satisfactory 

 as there is evidence of some action at the boundary between the 

 gold size and the glycerin. 



My brother, A. J. Curwen, has discovered that globules of pure 

 water or formalin water, copper acetate solution, etc., can be 

 readily sealed in the same manner by first turning a ring of 

 xylol balsam on the slip of the diameter of the globules when 

 compressed by the cover-glass. The effect of this ring is to 

 prevent the globule of water being shifted by the balsam when 

 running in. A considerable number of successful mounts of 

 algae have been made in this manner. Mr. Eoom has been 

 sealing glycerin with balsam or gold size and using three small 

 disks of red wax for spacing which can be compressed by pressing 

 on the cover-glass until the desired thickness is obtained. Care 

 would have to be taken to avoid compressing one spacing disk 

 more than another, as it is, of course, essential that the cover 

 should be parallel to the slip in order to avoid displacement of 

 the globule. 



At the 569th Ordinary Meeting of the Club, held on April 11th, 

 the President, Mr. D. J. Scourfield, F.Z.S., F.E.M.S., in the chair. 



