34 CANADA BALSAM FOR MOUNTING SPECIMENS. 



mixed with an equal quantity of distilled water saturated 

 with camphor, and strained through fine linen." 



Mr. Ralfs recommends bay-salt and alum, of each one 

 grain, dissolved in one ounce of distilled water. 



One ounce of acetate of alumina dissolved in four 

 ounces of distilled water, is said to be a good preserva- 

 tive of delicate colours. 



Canada balsam, for some purposes, has been fre- 

 quently used ; but, though this is a most excel- 

 lent medium for many plants, it unfortunately ren- 

 ders the delicate tissues of some Algse so extremely 

 transparent, as to make them invisible under the micro- 

 scope. Yet it has been found to answer extremely 

 well for the brown marine Algse (Melanospermese), as 

 well as the red (Rhodospermese). 



For the green series (Chlorospermeee), and all the 

 fresh-water Algae, it is almost entirely inapplicable. 

 With any plants having white filaments, or spines, 

 whether among the red or green Algee, there is the 

 same objection. 



I have now in my possession several specimens of 

 Calithamnia, GrifMisiae, Polysiphonise, &c., mounted, 

 more than four years since, in Canada balsam, in which 

 the colour is most beautifully preserved. The method 

 to be pursued in mounting Algae in any of the watery 

 fluids, differs scarcely anything from the usual plan. 

 It is as follows : — I use slips of glass (selecting good, 



