VOL. LXXXVI.] PHILOSOPHICAL TRANSACTIONS. 7 J 



investigation will afford us many additional motives to believe them to be true seeds. 

 The first of these objections cannot stand the test of close examination. The 

 grains of the ceramiums, like those of the true fuci, fall at a proper period, which 

 Gaertner calls senium, but which others will call maturity. If gently squeezed, 

 they come forth from the little cavity where they are formed, and which they must 

 leave when ripe. They come forth whole, and disengaged from the mother, and 

 from every part of the frons ; they have therefore a skin of their own. They are 

 contained in a small uterus, proportionate to their size, which is of a temporary 

 existence, and for them alone ; where they are no doubt affixed by some placenta- 

 tion, from which, when they come to maturity, they are disengaged and fall. If 

 we add to these considerations, that of their existing there enveloped in a soft 

 juicy substance, all their difference from the seeds of the true fuci wholly disap- 

 pears * ; and a strong probability arises, that Gaertner's observations were made on 

 dry specimens, as well as with a mind not only impartial to his preconceived 

 theories. 



The 2d reason is of a more specious nature, and requires serious attention. 

 Animals are divided into oviparous and viviparous, and a generally received compa- 

 rison points out the seeds as the eggs in plants, and the gems as correspondent to 

 living-born foetuses. We cannot conceive, says Gaertner, an egg where the ani- 

 mal, when coming forth, does not leave the shell behind ; and in like manner we 

 cannot conceive a seed where the coats are not left behind in the germination. 

 The grains of the ulvae, ceramiums, &c. according to him, do not leave any coat 

 when they germinate, and are consequently gemmae carpomorphae. Every candid 

 naturalist will easily acknowledge, that we are not possessed of observations suffi- 

 ciently decisive to enable us to speak dogmatically, on phenomena so little obvious 

 as the germination of these grains. But I will not contest the fact, I will only 

 examine the principle. This general rule, of judging whether these grains be seeds 

 or gems, by their leaving their coats in the germination, or not, is contradicted by 

 nature, both in the instance of gems, and in that of eggs. All gems, properly 

 so called, throw off .their scaly hybernacula in the act of germinating. On the 

 contrary, the eggs of frogs and toads leave no coat at all in their hatching, because 

 they are possessed of none. Their very viscous albumen answers, in such an ele- 

 ment as water, all the purposes the testa accomplishes in other eggs. Allowing 

 Gaertner the exactness of his observation concerning our plants, the analogy be- 

 tween these submersed algae and the aquatic oviparous quadrupeds would be strik- 

 ing, since both those plants and these animals are capable, from their structure, of 

 being nourished by absorption ; their embryos are hatched in the same element, and 

 equally surrounded by a tenacious mucous substance, without any exterior coats. 

 If the spawn of frogs be eggs, the grains of these plants must be seeds. 



* I have made mention of the ceramiums in this paper only to follow Gaertner through his objections. 

 This genus, first made by Donati, adopted by Adanson, and Gaertner, has in reality scarcely any dif- 

 ference from the fuci. — Orig. 



