BOTANICAL TECHNIQUE 637 



in the concentrate. The turpentine at 10 per cent, concentration 

 is excessively sensitive to atmospheric moisture, absorbing it and 

 clouding readily. The concentrate is less sensitive. The method 

 eliminates the critical alcohol-xj'lol transfer; the disadvantages 

 are (1) critical absolute-turpentine transfer, (2) slow hardening 

 of mounts, (3) few suitable stains, (4) a slightly lower refractive 

 index (1-542) than Canada balsam (1-547). 



2, Balsam Infiltration Method (Taylor). From absolute alcohol, 

 transfer through a series of six to ten alcohol-xylol mixtures 

 (5 : 1, 4 : 2, etc., or 9 : 1, 8 : 2, etc.) five minutes each, and into 

 xylol. Make two to three changes in xylol. Then place in very 

 dilute Canada, or better, damar balsam of a concentration a fifth 

 (or less) of that ordinarily used, allow to concentrate, and then 

 mount. The transfer to the balsam solution is critical. Con- 

 centration requires two days, rarely more. 



