36 INTRODUCTION. 



' to adopt the opinion that the two sorts of fructificatiou 

 observable among them are the first attempts at the 

 agency which in higher plants perform the office of sexes, 

 without, however, having their qualities established, and 

 each capable of producing a new plant, without the aid of 

 the other/ 



" M. Decaisne seems also to have altered his opinion on 

 tliis subject, for lie and M. Thuret now describe what they 

 suppose to be sexual organs in Fucus serratns and other 

 species, to which they even apply the Linnean names Monce- 

 cious and Dioecious. They describe the conceptacles of the 

 males as being filled with articulated filaments, bearing 

 numerous antheridia in tlie form of vesicles containing red 

 granules. ^ These antheridia are expelled by the orifice 

 of the conceptacles ; if we examine them with a micro- 

 scope, we see issue from one of their extremities trans- 

 parent somewhat pear-shaped bodies, each enclosing a red 

 granule. Every one of such bodies is furnished with very 

 thin cilia, by means of which it moves with very great 

 activity.' Such bodies are regarded as analogous to the 

 spiral threads of mosses and other cryptogamic plants. 

 Indeed, accordinir to M. Thuret, such threads are also 

 furnished with ciliary locomotive organs. But what proof 



