248 



The Philippine Journal of Science 



1918 



The advantage of the foregoing procedure is that it provides 

 ample contact of the cementing medium with both cover and 

 slide and affords ample support for the cover against such pres- 

 sure as it may be necessary to employ for occasional cleaning 

 of the upper surface of the cover. Further, it provides for the 

 exclusion of specimens from beneath that part of the cover glass 

 which may be overlapped by the sealing ring. And the sealing 

 ring may be kept entirely below the level of the upper side of 

 the cover in case it is desired to employ close- working objectives 

 for the marginal regions of the mount. 



THE OSTERHOUT MOUNTING METHOD ADAPTED TO VOLVOCACEAE 



A rapid method of mounting in aqueous media which was 

 devised by Osterhout 3 is rendered more suitable for the larger 

 Volvocaceae by the use of glass rodlets for cover-glass supports. 

 It has been employed successfully for mounting stained speci- 

 mens in nearly concentrated glycerin. I will describe the method 

 as modified for my special purpose. 



For each mount a larger cover glass, 18 mm square, and a 

 smaller one, 11 mm square, are used. A pair of covers 22 and 15 

 mm square would give the same margin. It is advantageous to 

 provide a special slide for the preliminary manipulations. This 



Fig. 1. Special slide with preparation ready for transfer to permanent slide. Glass or 

 paper guides cemented in place, a; larger cover, b; balsam droplets, c; glass rodlets, d; 

 smaller cover placed over the ruled square on the slide, e; depression in slide for forceps, f; 

 material, the nine round bodies. Somewhat enlarged. 



may consist of a slide with a small hollow-ground depression, 

 to which are affixed glass or paper guides for holding the larger 

 cover glass in position concentrically over a ruled square of the 

 size of the smaller cover, the guides and ruled square being so 

 placed that the hollow in the slide admits the tip of a forceps 

 point under the margin of the larger cover glass. This ar- 



' Osterhout, W. J. V., Contributions to cytological technique, Univ. 

 California Publ. Bot. 2 (1904) 73-90. 



