14 Mr. H. J. Carter on the Development of Gonidia 



normal process of reproduction in Achlj/a prolifei-a*, as well as 

 in Cladophora fflomerataf, &c. ; and therefore it seems not im- 

 possible that, under certain circumstances, the gonidia of Nitella 

 might produce a new plant ; but this has not yet been proved ; 

 neither have we, I think, an instance on record of the resting 

 spore, which commonly developes a new filament, dividing upon 

 some occasions into small spores, which can also each produce a 

 new filament. Although AgardhJ saw the resting spore of 

 Spirogyra divide up into small spores, while he was endeavouring 

 to see the single filament developed from it which Vaucher 

 had described, he does not state whether or not these sporules 

 germinated. One difference between the resting spore and the 

 gonidia is, that in the former the process of development is very 

 slow, and in the latter very fast ; hence it may be that the 

 resting spore is only resolved into gonidia when it does not 

 " go its full time,^^ so to wi'itc, and therefore produces an 

 abortive progeny ; while in Achlya prolifera, where the spore 

 does not wait until the next season for development, this is the 

 normal process, and each small spore produces a new indi- 

 vidual. 



Since writing the above, I have been able to confirm some 

 more observations which I had made some months since respect- 

 ing another kind of passage of the cell-contents of Nitella into 

 ciliated sacs, viz. — 



About three weeks after gathering plants of Nitella and 

 pla(;ing them in a basin of water, the green layer of the long- 

 slender internodcs becomes se{)aratcd from the cell-wall, and 

 gathered up into dark, spherical bodies, averaging about the 

 100th part of an inch in diameter, or large enough to be seen 

 by the unassisted eye. 



These at first move up and down the internode with the rapidity 

 of animalcules, but afterwards lose this power of locomotion and 

 become stationary. They then present, under the microscope, 

 the appearance of resting spores ; that is to say, they consist of 

 a dark green, globular, grumous mass, invested with a trans- 

 parent spherical cell. This green mass, in all that I have 

 examined, has been in an active state of rotation, first one way 

 and then the other, by means of short cilia which covered its 

 surface, like those on the spore of Vauclieria Ungeri^. On being 

 crushed bc^tween two pieces of glass, this mass was found to 

 consist chicfiy of pellets of difi"erent sizes, of a deep green 

 colour (formed of groups of green disks, respectively surrounded 



* Thurct, Ann. des Sc. Nat. ?>- Ser. t. 14. pi. IfJ, Botan. 



t linger, idem, 2^' Sor. t. ii. p. 1, Botan. 



t Ann. des Sc. Nat. 2'' Ser. vi. VJ] . 



§ Thuret, Ann. des Sc. Nat. 2'' Ser. t. xix. )). 266, Botan. 



