90 



him to be the male generative system, which performs on the 

 other portion of the endochrome a true impregnation. This 

 view would appear however to be a mere hypothesis, when we 

 observe the formation of the spores in the Spirogyrce by con- 

 jugation, as in these plants all the cells contain the larger glo- 

 bules, which M. Morren regards as the male generative sy- 

 stem, and yet germinating seeds are only formed in the con- 

 jugated cells. 



I have published* some observations on the brownish ve- 

 sicles which characterize the cavities at the extremities of the 

 Closterice by their active molecular movement. Gruithuisen 

 discovered this motion twenty-six years ago, and he subse- 

 quently observed a current of minute globules which occur at 

 the margins of the Closteria, and may be compared to that 

 in the Charae. I pursued these observations somewhat fur- 

 ther, and remarked that they consist in two currents of mi- 

 nute globules proceeding in opposite directions, and are evi- 

 dent both on the concave and convex sides of the Closterice. 

 Other observations showed that these brownish vesicles pass 

 out of the cavities at the extremities of the horns, and that 

 they can change from their constant and lively molecular 

 movement into a merely progressive one, and vice versa ; for 

 they re-assume their molecular movement so soon as they 

 have returned from their progressive motion into the cavity 

 of the extremity. The observations for this view are spe- 

 cially given in the work above-mentioned, and I have subse- 

 quently made several similar observations on the cellular sap 

 globules of higher organized plants, which are enumerated in 

 the second volume of my Vegetable Physiology, in the chapter 

 on the rotatory current in cells. 



Sir W. J. Hooker t has brought together numerous obser- 

 vations of great interest on the duration of the germinating 

 power of seeds, on which subject various, and frequently almost 

 incredible notices have appeared of late years. In the first place, 

 the observations of Ch. des Moulins, from the memoirs of the 

 Linnaean Society of Bordeaux, (which unfortunately are not at 



* Wiegmann's Arcliiv, 1 837, p. 426. 



f Information respecting seeds which have been found in Roman tombs, 

 and which have retained their powers of germination, &c. Companion to 

 the Botanical Magazine, 1837, vol. ii. p. 293. 



