30 STRUCTURE OF THE GILL- PLATES OF AGARICS. 



Basidia. — The basidia are cells which vary within sufficiently 

 restricted limits ; they are in general widened towards the summit, 

 and more or less swollen or slender, rarely of an equal size from the 

 base to the summit. Upon the hymenium of Agaricus ceriums we 

 have seen basidia slightly compressed at the centre to take a 

 biventral form, but this form is rare. 



The basidia contain a granular liquid charged with little drops of 

 oil, sometimes slightly coloured ; this liquid passes through the 

 sterigmata or sporophores, little organs ordinarily four in number, 

 superposed upon the basidia, and from the summit of which the 

 spores originate. It is a sort of hollow funiculus, varying in 

 length, sometimes slender, sometimes wide and funnel-shaped, and 

 joinedto thebasidiuin by the wide part, sometimes describing a curve 

 in the form of an ox's horn. During the early stage of the spore it 

 is seen, as well as the sterigmata, to be filled with the granulations 

 which were accumulated in the basidium. According to Corda, 

 each sterigmata always develops one spore at a time, and some- 

 times one after another ; although direct observation has not yet 

 demonstrated this fact to me, it seems to be very probable, for we 

 see the old basidia, which have employed their granulous contents 

 in the fabrication of spores, present nothing in their interior but a 

 clear and transparent liquid.* 



When a basidium bearing ripe spores ready to be detached is 

 found still filled with the granulous plasma intended for the spores, 

 it is to be presumed that it will serve for a second formation, the 

 existing spores being entirely closed, and maintaining only a very 

 feeble connection of endosmose with the sterigmata. We see, 

 besides, some basidia, the plasma of which has been partly used, 

 keep only three-fourths or a half of their cavity filled with granu- 

 lations, as I have observed, and figured in a section of the gills of 

 Agaricus murinus ; this diminution of the contents has very likely 

 a connection with the number of spores formed. If we were able 

 to assure ourselves that amongst the tetraspored basidia there are 



they surround ; the receptacle takes a concave form to envelope the hymenium, 

 and this form subsists among the species with bymenophores exposed on the ex- 

 terior (Helvella, Morcliella, &c.) by the formation of secondary or alveolous 

 cavities. 



Amongst the Hymenomycetes, the spore seems, on the contrary, endowed with 

 a centrifugal force which urges it to the exterior of the basidium ; the basidium 

 tends to raise itself above the hymenium — at least for the whole height of the 

 sterigmata, and most frequently, for even much more. In fine, the receptacle 

 tends always to bear the hymenium to the exterior, by offering it the convex 

 surfaces of gills with pointed ramifications The Exidece and the Cyphellce seem 

 to break this law by reason of their concave shape, but it is always verified in the 

 hymenium, and we are accustomed to meet everywhere, in the organic kingdoms, 

 these aberrations of types which seem designed only to concur in a sort of har- 

 monic symmetry, by recalling to us, in certain sections, and among certain 

 groups, forms which belong to others more or less removed from them. 



* " Whilst the basidium, fulfilling the function which is deputed to it, gives 

 birth to the spores, it empties itself for their use of the plastic matters which 

 were elaborated or accumulated within it, and, when the reproductive bodies have 

 left it, it is only a colourless cell of an extreme transparsncy." — (Tulasne, Sur 

 V Organisation, &c.) 



