THE HIGHER CRYPTOGAMIA. 289 



in a spiral maimer, covering the spore entirely as at first. 

 It may easily be seen by the examination of detached 

 fragments of elaters that the rolling inwards is not accom- 

 panied by any contraction of the concave side. It follows 

 from this that the extension of the elaters depends upon a 

 relatively greater contraction of the outer layers of their 

 tissue, a contraction which is completely balanced by 

 moistening the elaters. By moistening the ripe dry spores 

 the elaters are rapidly rolled inwards ; almost immediately 

 afterwards they become unrolled. Sulphuric acid and water 

 also causes a rolling inwards of the elaters : when concen- 

 trated to a certain extent it destroys only the inner layers. 

 The thin outermost layer, which during the formation of 

 the inner layer was coloured yellow by iodized chloride of 

 zinc (Pringsheim's ' Elater-cuticle/ Bot. Zeit., 1853, p. 

 244), remains behind in the form of a loose band. The 

 second (now the outermost) membrane of the spore, be- 

 comes distended and detached from the middle layer by 

 the action of sulphuric acid, whether concentrated F or 

 diluted. The inner spore-membrane is largely distended 

 by concentrated sulphuric acid, so that it soon ruptures 

 both the outer membranes, and emerges with the spore- 

 contents in the form of a gelatinous globule (PL XXXVIII, 

 fig. 11). The two outer membranes are not affected by 

 heated sulphuric acid, not even by remaining in the acid 

 for ten days. The outer layer under such circumstances 

 remains at first as clear as glass, and afterwards only ex- 

 hibits a smoky-grey colour and a granular consistency of 

 the outer surface. The inner layer which is finely granular 

 is coloured deep brown. After the rupture of the spore 

 all its membranes contract considerably, so that the diameter 

 of their inner cavity is only about half the previous size. If 

 the rupture of the spore is effected by treatment with sul- 

 phuric acid the contraction of the middle (third) mem- 

 brane, and consequently the elasticity upon which this 

 contraction rests, appears to be altogether unaffected, and 

 that of the outer membrane is but slightly acted on. After 

 the bursting, by pressure, of the fresh, ripe, detached spore, 

 the outer boundary only of the innermost (fourth) mem- 

 brane is sharply defined ; the inner side of the latter mem- 



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