of the Spores in Spirogyra. 313 



mation and unfolding*; yet during this time of apparent rest, 

 processes are unceasingly active in the interior of that germ, 

 not immediately manifesting themselves to the eye, but resulting 

 in effects, which may be detected in the spores of Spirogyra in 

 demonstrable alterations of the contents and of the mem- 

 branes of old spores. Immediately after formation, the spore 

 possesses only one single, perfectly colourless, thin membrane, 

 which, as is shown by the acquisition of a blue colour with 

 iodine and sulphuric acidf, is composed of pure cellulose. In 

 many spores, this membrane is still so thin for a short time 

 after the formation of the spore, that it is yet incapable of with- 

 standing the strong endosmose excited by the addition of sul- 

 phuric acid, and bursts at some' point, allowing the escape of the 

 contents. The contents of the new-formed spores consist of 

 the almost unchanged spiral bands of the cells concerned in the 

 formation of the spore. The spiral bands are, indeed, contracted 

 far more closely together than in the filament-cells, but re- 

 tain even their form scarcely changed. As in the spiral bands 

 of the Spiroffyra-ceW, so also the spores contain numerous large 

 and small starch-granules, lying in a layer of the so-called amor- 

 phous chlorophyll (extractable by absolute alcohol), which ap- 

 pears to be deposited upon the finely granular protoplasm (a 

 mixture of oil and proteine-substance, albumen ?), visible after 

 the removal of the chlorophyll. The older the spores grow, the 

 more does the form of the spiral bands in their interior disap- 

 pear, and their contents become imiformly diffused over the 

 entire inner surface of the spore-membrane. Finally, just before 

 the germination, the original spiral arrangement of the contents 

 is still indistinctly indicated by several close spiral streaks in 

 the coating, spread uniformly over the wall (fig. 1 a, b, PI. VIII.). 

 It is a pecuhar circumstance, that during this time the spiral 

 arrangement of the contents of the spore presents itself, some- 

 times distinctly and sometimes indistinctly, and almost wholly 

 vanishes at the moment of germination, but always appears with 

 surprising clearness when the spores are left for some time in 

 glycerine, or are allowed to become perfectly dried up (PI. VIII. 



* This long repose between formation and development is perhaps 

 the only character which the spores of the Cryptogamia have in common 

 with the seeds of the Phanerogamia. But the true analogue also of the 

 Cryptogamic spore in the Phanerogamia, the pollen, is well known to be 

 capable of maintaining its germinative form through long periods of rest. 



t I prefer the application of iodine and sulphuric acid to the apparently 

 more convenient use of the so-called chloride of zinc solution (chloride of 

 zinc, iodine and iodide of potassium), since the former is a much stronger 

 and more certain reagent for cellulose, and produces the blue colour without 

 previous application of an acid or an alkali, even in cases where the chloride 

 of zinc solution is ineffective. 



