The Lichens of Victoria. 147 



The chemicnl le-agents used in examining specimens are 

 tlecrieil by some liclienologists as being unreliable. Tliey 

 are, however, v'aluable assistants in determining species, 

 although they may not be absolutely conclusiv^e taken b}'- 

 themselves. The usual formula by which the solution of 

 iodine (signified by the lettei- 1), is prepared is — iodine, 1 gr., 

 iod. potass., 3 grs., distilled water, | oz. For all practical 

 purposes, however, a strong enough solution is made by 

 j)utting a few grains of i(xline into a small phial of water 

 and allowing it to stand a day or so. The solution needs to 

 be kept in a glass-stoppered bottle of dark colour, or covered 

 with tin foil to exclude light. Hypochlorite of lime (signi- 

 fied by the letter C), is prei-»ared by putting a small j»ortion 

 of chloride of lime into a phial of water, and shaking it. 

 When the fluid clarifies, it is read}^ for use. Hydrate 

 of potash (signified by the letter K), is composed of equal 

 weights of water and caustic potash. It may be well 

 to intorm the beginner that when the water is added 

 to the caustic potash, a good deal of heat is evolved. It is 

 well, therefore, to previously warm the bottle, lest the 

 sudden heat should break it. The supply of caustic potash 

 needs to be kept from the air by beeswax round the stopper 

 of the bottle in which it is preserved. The hydrate should 

 also be kept in a stoppei-ed ]ihial, and must be used care- 

 fully, as it corrodes clothing, »Scc. These re-agents may be 

 applied, a drop at a time, by means of thin rods of glass ; 

 keeping each rod for its own solution, and wiping them dry 

 on an old rag after using them. 



The application of C and K is either to the surface of the 

 plant or to the medulla. The younger part of the thallus is 

 the best for examination. In cold weather, a little heat 

 needs to be applied to hasten the action. This may be done 

 either by placing the ])hial with the solution in a cup of 

 warm water, or by putting the ])art under examination close 

 to the mouth and breathing heavily and repeatedly on it 

 after touching it with the solution. First apply C to a 

 portion of the thallus, and note the result. Then to another 

 portion apply K, and, after watching the effect a short 

 while, add C and note the results. To examine the action 

 on the medulla, scrape off' a portion of the cortex from 

 another part of the thallus, and apply K and C in the 

 same manner. The more freshly made the solutions are, 

 and the more carefully they are kept from the air, the more 

 reliable are the results. 



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