774 TRANSACTIONS OF SECTION Kj 



directions in which progress could be made at once, and to provision which should 

 be made for the advancement of the study of the British flora with as little delay 

 as possible. There is, I feel assured, the means of making far more rapid and 

 satisfactory progress towards the goal than has yet been accomplished. Many 

 persons are interested in the subject, and would gladly give their aid if they 

 knew in what way to employ it to the best purpose. As a nation we are apt to 

 trust to individual rather than to combined efforts, and to waste much time and 

 labour in consequence, with discouragement of many who would gladly share the 

 labour in a scheme in which definite parts of the work could be undertaken by 

 them. 



I believe that a well-organised botanical survey of the British Islands would 

 give results of great scientific value, and that there is need for it. I believe, also, 

 that means exist to permit of its being carried through. There is no ground 

 to expect that it will be undertaken on the same terms as the Geological Survey. 

 A biological survey must be accomplished by voluntary effort, with possibly some 

 help towards meeting necessary expenses of equipment from funds which are 

 available for assistance in scientific research. Is such a survey of it an object 

 fully in accord with the objects for which the British Association exists? In 

 the belief that it is so, I ask you to consider whether such a survey should not 

 be undertaken ; and, if you approve the proposal, I further ask that a committee 

 be appointed to report on what steps should be taken towards organising such a 

 survey, and preparing materials for a national flora of the British Islands. 



The following Papere were read :— 



1. On the Function and Fate of the Cystidia of Coprinus atramentarius. 

 By Professor A. H. Reginald Buller, D.Sc., Ph.D., F.R.S.C. 



Brefcld, 1 in giving an account of the life-history of Coprinus stercorarius, 

 made the suggestion that the cystidia which he observed in that species may 

 possibly act as props to keep the gills, when stretching, from pressing against 

 one another. 



Hitherto the fate of the cystidia of the Coprini has been a mystery. Worthing- 

 ton Smith 2 stated that the cystidia are male organs, that they fall to the ground, 

 and that they there liberate spermatozoa, which fertilise the spores. 



In the light of my recent discoveries concerning the mode of liberation of the 

 spores of the Coprini, 3 I have investigated the function and fate of the cystidia of 

 Coprinus atramentarius, and have come to the following conclusions : — 



The gills of Coprinus atramentarius arc of groat width and of extreme thin- 

 ness, and consequently are very flexible. Numerous long cystidia stretch between 

 and connect adjacent gills, the general surfaces of which thus become separated 

 by an interlamellar space about 0"10 mm. wide. The cystidia serve as props, 

 firstly, to keep the gills from touching one another during spore development; 

 and, secondly, to provide sufficient interlamellar space for the free escape of the 

 spores from between the gills during their discharge. 



The cystidia do not drop out of the gills when mature. Their disappearance 

 is due to auto-digestion. Excluding the cystidia, the gills undergo auto-digestion 

 from below upwards in the manner that I 4 have already described for Cojmnus 

 romatus. Each cystidium begins to undergo auto-digestion as soon as it comes 

 to be situated about 0'5 mm. above the upwardly progressing general zone of 

 auto-digestion, and about forty minutes or so before the basidia and paraphyses 

 in its immediate vicinity. During their auto-digestion the cystidia become pro- 

 gressively thinner, their fluid-contents are apparently absorbed by neighbouring 

 cells, and they are finally withdrawn in a much reduced state to the gill sides, 

 where their destruction is completed. 



The cystidia, owing to their early auto-digestion, never persist until the 



1 0. Brefeld, Untcrsachungen, Heft III., 1887, pp. 57 and 58. 

 * W. Smith, Grevillea, vol. iv., 1875-76, p. 60 ; also vol. x., 1881, p. 78. 

 8 A. H. R. Buller, Researches on Fungi, London, 1909, pp. 196-210. 

 4 TjCc, cit. 



