12 STRUCTURE OF AGARICS. 



the pileus was of an almost black sepia colour. Ordinarily this 

 Agaric is white, at other times a little dirty. A figure by Delile 

 shows a like phenomenon of colouration produced in this same 

 species, but with less intensity, upon an individual found also 

 during the month of December. As I am assured, by microscopic 

 study, there is no new production of cellular elements, but simply 

 a greater agglomeration of pigmentary granules. Finally, during 

 a herborization, made in the beech woods of the Lozere, at a tem- 

 perature of 5 to 6 degrees, I have been struck with the deep 

 colouration of Agaricus melleus and Agaricus lateritius, SchaBff., 

 which were to be seen by hundreds, and the aspect of which 

 differed very much from the same species found in the woods of 

 inferior zones, during the fine days of autumn. 



The result of numerous observations makes me certain that 

 although the cold has an influence upon the intensity of the 

 colouration among the Agarics, it does not follow that, in certain 

 given conditions, an observer cannot, in the middle of winter, find 

 an example of a normal colour, perhaps even more clear; it may be 

 caused by its being shaded or placed in the neighbourhood of a 

 source of heat, causing the body to develop in fermentation, the 

 dunghill for example ; an individual so found is placed in such 

 conditions with few exceptions. If one cannot find a sufficient 

 reason in the external circumstances, it follows then to recall the 

 contingence of physiological phenomena, the limits of variation of 

 which escape us, because of not knowing the exact causes. The 

 phenomena due to the atmospheric influences ought to be submitted 

 to some very numerous observations, and not to draw conclusions 

 from isolated facts. 



As to the influence of light upon the colouration of vegetables, 

 one may believe that it is much more upon the green matter which 

 it acts than upon the substances which colour the petals or other 

 organs. A herborization in the oil mines of Rochebelle, near Alais, 

 has enabled me to prove the little influence of the deprivation of 

 light upon the colouring matters of Fungi. I have found at 80 

 metres depth, in the most complete obscurity, almost a kilometre 

 from the entrance shaft, an Agaric allied to Agaricus conopilus, Fr., 

 presenting upon the pileus the fawn-colour habitual to this Agaric. 

 Some Polyporei reduced to a crustaceous expansion, with some ves- 

 tiges of pores, have offered to me, in the same conditions, a sul- 

 phury tint. Moreover, the figures given by authors who are spe- 

 cially occupied with the fungi of mines, demonstrate this fact. F. 

 Hoffmann has represented in his " Vegetabilia in Hercynia? subter- 

 raneis collecta," an Agaric which appears rather like Agaiicus gale- 

 ricvlatus, Scop., this species, called by him Agaricus myin us (pi. iii.), 

 is much coloured, also Agaricus u?tdvlatus, given in pi. iv. of the 

 same work. The want of light which acts so little upon the 

 colouration, has it more effect upon the general vegetation ? " That 

 which is most evident," says E. P. Fries, "up to what point the 



