Two-sporcd luisiiliti. .1. -I. rcarsoii. 45 



Professor lUilIer's illuminating^- biolos^ical studies and by 

 the unfailin^r kindness and severely critical altitude of our 

 hon. secretary, Mr. Carleton Rea. 1 have also been helped 

 by the use of an unusually hij^^h-powered eye-piece (Orth. 

 Ok n. Kellner l'V^i5.) wiiich 1 obtained last year for my 

 microscojX\ This has enabled me to observe the ^nll both 

 in section and on the flat face without exercisinjj;- as much, 

 skill as is expected from the professional microscopist. I^ne 

 razor sections are rarely necessary. The g\\\ when observed 

 on the flat will be seen to have a regular spacing for the 

 spores, either like a series of double-four dominoes, when 

 the basidia are quadrisporous, or they will be spaced in 

 pairs when the basidia are bisporous. In most species there 

 is no difficulty in making the observation. In some, 

 however, the basidia project so little and the spores are so 

 transparent, that a section must be made. Rough sections 

 are usually sufficient, and no cover glass need be used, it 

 is better always to make the observations both on the flat 

 and in section, thus avoiding the chance of errors. The use 

 of the high power eye-piece combined with a low-power 

 objective enables one to make observations ([uickly. This is 

 essential with the small fleeting Agarics. I have never used 

 this eve-piece for measuring spores or cyslidia but only for 

 observations on the naked gill. When the high-power 

 objective is used, as it must be for measuring spores, one 

 can get clearer definition with a less powerful eye-piece. 



The advantage, however, of using a low powered objective 

 is that one can get better illumination and look at the gill 

 in the natural state without making fine sections or distort- 

 ing the fibres with a cover glass. Such observations are con- 

 fessedly imperfect and possibly of only very restricted 

 scientific value. They are better than nothing, and as they 

 are within reach of people without laboratory training or 

 experience, it seems desirable to encourage them. For it Is 

 important that field mycologists should use the microscope 

 more than they do ; it adds so enormously to the interest 

 and value of their work. What a revelation it is for instance 

 to see the horned cystidia of Pluteus cervinus or the spacing 

 pegs of many of the Coprini. A knowledge of the 

 existence of cystidia gives a new meaning to the fringe of 

 colour seen so often on the gill edge and leads one to think 

 thev may be organs of excretion or transpiration. Other 

 kinds probablv have a totally different function. In fact 

 endless biological problems are open to the student, who 

 need not be repelled bv the thought of the mysterious 

 methods of the professional worker, with his accjuired skill 

 in cutting sections and using staining agents. 



