of the Spores in Spirogyra. 297 



of Algae and organisms allied to them, the limits of its extension 

 ^eing at present indeterminable. 



i). I have made an observation similar to that on the origin of 

 moving spores in the cells of the young SpirogyrcB (PI. IX. fig. 8) 

 in the spores of CEdogonium tumidulum, after they had already 

 come to rest and had formed a radical prolongation at one end, 

 as in the commencement of germination. Thuret *, in his 

 splendid illustrations of the moving spores of Algse, has figured 

 two locomotive, but already resting spores of (Edogonium vest' 

 catum (Link, not Kiitzing), from the summits of which the mem- 

 brane has separated all round, like a lid, by a transverse slit, and 

 ^e remarks that the green contents of such spores had always 

 -yanished. I had an opportunity of repeating this observation 

 (fig. 12 e), but found that the contents of such spores, before 

 Vanishing out of the upper oi'ifice^ had become metamorphosed 

 into a number of little moving spores, exactly resembling those 

 ;^?hich I had found in Spirogyra jugalis (fig. 12 b, c). I could 

 not 'trace completely the transformation of the green contents of 

 these spores into the moving cells ; but the appearance of similar 

 large cells with brown nuclei and lighter contents separate from 

 the nucleus, before the formation of the moving cells (fig. 12 d, d), 

 exactly as in Spirogyra jugalis, led me to conjecture that their 

 formation takes place in the same way as in that case. 



The moving cells exactly resemble those of Spirogyra jugalis 

 va shape, size, and motion. I have not, indeed, observed their 

 exit from the spore which comes to rest, myself, but have fre- 

 quently found the empty spore with the detached lid j the place, 

 also, where the lid is to separate subsequently is very frequently 

 indicated beforehand, and I often saw the lid already separated 

 all round, but not yet removed (fig. 12 a, d), while the transfor- 

 mation of the contents of the spore into moving cells was yet 

 incomplete. If, as is probable, the clear cellules of (Edogonium 

 are capable of propagating, these plants also may present, be- 

 sides the resting form of spore which is produced in the enlarged 

 cells, and whose germination is equally unknown at present, and 

 the ordinary moving form of spore, a third equally mobile form 

 of spore. 



Of analogous occurrences in plants of other famihes, I will 

 further refer to those observations which I have made on Achlya 

 prolifera f, standing so nearly allied to the Algse in its physio- 

 logical phsenomena, because these leave no doubt as to i\ie power 

 af germination of the daughter-spores produced in the spores , 



* Ann. des Sc. Nat. 1850, Ser. 3. xiv. 26. tab. 14. fig. 9. 

 t Die Entwickl. der Achlya prolifera, Nov. Acta A. N. C. xxiii. pars 1, 

 397. 



Ann. ^ Mag. N. Hist. Ser. 2. Vol. xi. 20 



