2QO BY THE DEEP SEA. 



receptacles, and they contain the elements necessary for the 

 production of spores, whereby the plant is reproduced. In 

 one plant these elements will be all male (antherids) , in another 

 all female (pogones). If you will examine one of these club- 

 shaped orange organs with your pocket-lens, you will observe 

 that its surface is pitted with a considerable number of round 

 pores, and if you cut across the whole body just on the edge 

 of one of these pores, you will find it communicates with a 

 globular cell in the substance of the receptacle. These cells 

 are known as conceptacles, and their number corresponds to 

 that of the pores. Their walls are clothed with a felt-work of 

 threads, upon which are borne, in the male conceptacles, 

 minute egg-shaped cells (antherids), which ultimately burst, 

 and set free thirty-two or sixty-four tadpole -like bodies (anther- 

 ozoids), each with two tail-like threads (cilia) attached to the 

 under part. By the lashing of these organs they make their 

 way out thrpugh the pore of the receptacle into the sea. 



With the development of the antherozoids, a similar activity 

 has taken place in the female conceptacles, where bodies 

 approaching more to an ellipsoidal or spherical form (oogones) 

 have appeared, and their contents have broken up into two, 

 four, or eight smaller bodies (the oospheres). On their escape 

 into the water, they are each surrounded by a number of the 

 antherozoids, which pierce the substance of the oosphere, 

 become absorbed in it, and so fertilise it. Development then 

 commences in the oosphere, and it gives rise to a new Fucus 

 plant. This form of reproduction is by no means common to 

 the whole class of seaweeds ; on the contrary, there are many 

 important variations of it, which for want of space we shall be 

 unable to refer to in detail. This is the highest type of repro- 

 duction in the Algae. 



The Channelled Wrack never exceeds a few inches in length, 

 but another species, which agrees with it to the extent of 

 possessing no mid-rib, varies from two to six feet. This is the 

 Knotted Wrack (Fucus nodosus), which may be at once 



