VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 73 



little dry, if put into certain fluids, are seen, by the help of the microscope, acting 

 in the same manner as when in the state of perfect farina. 



The plants whose fructification lies unsheltered under water are very few in num- 

 ber ; and such of them as have been hitherto thoroughly examined, (the cerato- 

 phyllum and the chara), have antherae furnished with mucous pollen, not bursting 

 in the fecundation. From the time of Dillenius it has been observed, that the 

 submersed antherae of the ceratophyllum never burst, but are found whole, though 

 the seeds be ripe *. If squeezed, they shed a soft and pulpous matter, like that 

 which is found in unripe antherae. Dillenius suspected that the fructification of the 

 chara being equally submersed, its antherae and pollen would be of the same nature 

 with the preceding, and observations have fully confirmed the conjectures of this 

 great naturalist. The antherae of the chara do not burst in fecundation ; its pollen 

 is mucus : the germen has no pistillum, and is probably fecundated through its 

 receptaculum, as there exists in each internodium, according to modern observa- 

 tions -j~, a chain of vessels which twist round the antherae and the fruit, and in 

 which a circulation of humours is visible, at least in the period of fructification. 



If pollen therefore, under the shape of farina, be unfit for fecundation in the 

 water ; if nature has taken a particular care to guard this operation from the pre- 

 sence of that element ; if pollen can exist in an active state under a mucus ap- 

 pearance ; and if the antherae of perfectly submersed flowers are nothing else than 

 closed vessels filled with mucus pollen ; what doubt can we entertain, that the 

 mucilaginous vesicles of the submersed algae, which contain also their seeds, are 

 antherae, and very appropriate to the nature and situation of these plants ? An 

 observation made by Gleichen shows more clearly the propriety of such a fructifi- 

 cation. The pollen of any flower, when put into water, in a very short time be- 

 gins to move, and its particles agitate themselves in every direction, perfectly re- 

 sembling the most lively animalcula. Their activity in this state lasts some time ; 

 but if the least quantity of salt be put into the liquor, death quickly ensues, from 

 which they never more recover J. This inclosed mucilaginous fructification was 

 therefore the only one which could ensure existence to vegetables living chiefly in 

 sea-water, with which their mucus is found to be immiscible §. 



A still more urgent consideration will, I hope, determine those who may hesitate 

 to consider the mucus of these plants as pollen, and the vesicles which contain it 

 as antherae. The parts of fructification, in all plants, are temporary, and their 

 existence is relative to their particular functions, and to each other. The moment 

 the fecundation happens is a moment of crisis : henceforth the fecundated parts 

 proceed to grow and perfect themselves, the fecundating ones change and decay. 

 This is a general law of nature, to which we know no exception, nor can any be 

 easily conceived to exist. We must remark, that there is an epoch when the 

 mucous substance in the vesicles of the fuci suffers a material alteration, but the 



* Plantae Gissenses, page*)!, f Corti, Osserv. Microscop. Lucca, 1774. 



% Gleichen, Observ. Microscop. page 32. § Gmelin, Hut Fucorum, page 2?.*— Orig. 



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