of the Spores in Spirogyra. 215 



haps still lies. The detection of the three membranes of the 

 spore is very readily effected by the application of concentrated 

 potash. The spore does not burst when left in concentrated 

 solution of potash, but after a few daysj the three membranes 

 appear clearly separated from each other (fig. 6a & Z>). Under 

 these circumstances, the inner cellulose membrane {g, fig.6 « & b) 

 exhibits the remarkable property, otherwise found only in the 

 primordial utricle, of contracting by shrivelling together. It 

 surrounds the primordial utricle {h, fig. 6 6) with its contents 

 contracted into the middle of the cavity of the cell. The shrivel- 

 ling together of this cellulose membrane is often so strong, that 

 it is no longer capable of holding the contents, and these, dis- 

 solved by the potash, escape in large drops, of indefinite form, 

 into the interspace between the inmost and the middle yellow 

 membrane (i, fig. 6 b). And in the spores treated with potash, 

 after the latter has been washed out, the application of iodine 

 and sulphuric acid turns this third inmost membrane {ff, fig. 6 a 

 & b) bright blue, so that there can be no doubt of its chemical 

 constitution. 



The production of the two inner membranes in the spores 

 takes place in exact analogy to the universal formation of 

 secondary layers of thickening in vegetable cells; the middle, 

 yellow coat follows the outer primary coat, not only in position 

 but in structure, as a secondary deposit, and the deposition of the 

 inmost, in regard to its productive tertiary cellulose membrane, 

 occurs long after the formation of the yellow coat. Since Mohl's* 

 researches have demonstrated that cellulose is the basis of the 

 thickening layers of all vegetable cell-membranes, its reaction, 

 frequently hidden by infiltrated matters, reappearing clearly 

 after the removal of them by potash or nitric acid; it was 

 natural to conjecture that the yellow, middle membrane of the 

 spore would exhibit the cellulose reaction if properly treated. 

 But I only succeeded in demonstrating the cellulose in this 

 membrane after much trouble, for all the means I applied to 

 extract or destroy the colouring matter of this membrane were 

 at first ineffectual. Only after a longish digestion in aqua regia 

 was the yellow spore-membrane bleached, without being de- 

 stroyed. When the bleached spores, well washed with water to 

 remove the aqua regia, were treated with iodine and sulphuric 

 acid, the thick, middle, previously yellow membrane became blue. 

 The more perfectly the membrane was bleached by aqua regia, the 

 purer the blue colour acquired with iodine and sulphuric acid ; 

 the less perfect the bleaching was, the more the blue inclined to 

 green. This membrane certainly is one of those vegetable 

 membranes in which it is most difficult to demonstrate the well- 



* Botanische Zeitung, 1847j Trans, in Scientific Memoirs, vol. i. 2nd ser. 



