288 HOFMEISTER, ON 



than it previously was. It has borne a strong pressure 

 from the expanding cell-contents, and possesses a high 

 degree of elasticity. Its hitherto smooth outer surface 

 now exhibits very small protuberances which give it a 

 finely granular appearance. Its inner surface is covered 

 by a tolerably thick layer of semi-fluid hyaline matter, 

 which by hard pressure is partly driven out from the 

 fissure of the ruptured membrane. If a spore in the 

 above stage of development be taken fresh from the sporan- 

 gium and treated with caustic potash, the elaters swell 

 up ; the adjoining membrane is distended into a vesicle, 

 and usually becomes wrinkled. The third granular mem- 

 brane assumes a brown colour, but in other respects re- 

 mains unchanged. The fourth membrane, which is still 

 delicate, contracts round the cell-contents, and exhibits a 

 double outline.* The peripheral portion of the cell-con- 

 tents then assumes a red colour, which never extends so 

 far as the middle point of the cell, and which depends 

 upon the presence of tannin. f Sometimes in spores taken 

 from the same sporangium, like those just mentioned, the 

 innermost layer swells up under caustic potash, and remains 

 in contact with the granular lajev. The latter may then 

 be stripped off from the inner layer by friction with the 

 covering glass, and will be seen to be a closed vesicle sur- 

 rounding the cell- contents. Sulphuric acid immediately 

 destroys the elaters of such spores ; the next inner mem- 

 brane, like the third granular layer, thereupon expands 

 into a capacious vesicle, but resists the acid. The fourth 

 innermost layer swells, and becomes converted into gela- 

 tine, which after the rupture of the cell is immediately dis- 

 persed in the surrounding fluid. 



After the bursting of the ripe sporangia j the elaters, when 

 dry, are stretched out, remaining attached to the spore by 

 their median portion. When moistened they roll together 



* Sauio, 1. c, p. 665, who from its contractility, draws the conclusion that it 

 is a primordial utricle. 



f Sachs, ' Sitzungsb. Wiener. Acad.,' xxxvi, (1859) p. 21. Sanio has observed 

 that the red colour only affects the cell-contents, 1. c, p. 666. 



% The wall of the sporangia, which consists of one layer of cells, is trans- 

 formed into spiral cells. Compare Henderson, 'Trans. Linn. Soc., 5 v, xviii, 

 p. 567. 



