CONTRACTILE FILAMENTS OF AGARICUS MUSCARIA. 75 



with a needle and teasing it out in water, one sees that the cells, 

 of which the layer is composed, cross and interlace in a felt-like 

 manner. The cells are covered more or less with a yellowish 

 substance, which forms little warts projecting from the surface. 



The contractile filaments project in the same way from the 

 cell walls,' and immediately arrest the attention from the fact of 

 their being in continuous trembling movement. Various forms 

 of filament are shown in figs. 1 and 2 ; they consist of a trans- 

 lucent and highly refracting substance, which is certainly the 

 same as that of the little wart-like projections above mentioned.^ 

 They are usually of a simple cylindricial form, clubbed at the 

 free end, and vary extremely in length and diameter ; they also 

 present curious dumb-bell shaped forms. Both Hoff'mann and 

 de Bary describe a hollow canal running up the centre of some 

 of the filaments. I saw appearances which might be so inter- 

 preted, but I was not sure that it was not a deceptive optical 

 appearance. In many cases, as in fig. 1, the cells are incrusted 

 withdirty-looking accretions, which produce an irregular oruntidy 

 appearance. They seem to consist of the s«me material as the 

 translucent projections, but to have become opaque and granular. 



On the whole, the filaments of Agaricus present the closest 

 and most striking resemblance to those of Dipsacus ; I re- 

 peatedly remarked that I could not have distinguished one from 

 the other, although in other cases I noticed a ditt'erence in aspect. 



The behaviour of the filaments with reagents has been partly 

 investigated by Hoffmann. But unfortunately he does not mention 

 the strengths of the solutions which he employed. He found that 

 rapid contraction was produced by solution of caustic potash (kali- 

 lauge), by ammonia, spirit of wine, oxalic and nitric acids, chloride 

 of calcium, and sulphuric ether. Chloride of sodium produced slow 

 contraction; carbonate of potassium, contraction preceded by 

 lively extension and bending to and fro; sugar solution gradu- 

 ally added produced contraction. He states that the juice 

 squeezed from the stem of the fungus itself produces contraction, 

 though "monads and other infusoria" are not affected by it. 

 Hofi'mann describes a phenomenon which I have often seen in the 

 teasel, namely, the swelling up in water of a contracted filament, 

 and the formation of transparent bladders. This is the appear- 

 ance which I have compared to the formation of soap bubbles, 

 and which often results when a filament has been killed by 

 heat, acids, &c.^ 



The following experiments show that, as in the case of 



1 Tlieir size may be judged of by tlie drawings, fig. 1 and 2, wliich are 

 X 430. A moderately long filament measured about '07 mm. 



- Only a few of these are seen in the figs. ; they are shown in Ilolfmaun's 

 taf. xi, fig. 17. 



* Loc. cit., p. 250-51, fig. 5, plate xix. 



