384 



BOTANY OF THE LIVIiNG PLANT 



to form 64 nuclei, each of wfiich becomes the centre of a spermatozoid. 

 The cytoplasm divides into as many portions, and each is found to 

 contain a red eye-spot beside the nucleus (Fig. 324, 2). The contents 

 slip out when ripe from the ruptured outer wall, as a mass still sur- 

 rounded by the inner wall : this soon deliquesces, and sets them 



« k 



11 /\« u^ 



Fig. 32 ^. 

 Fiicus. I. group of antheridia. 2, part of an aiitheridiuni showiag developed 

 spermatozoids. 3, spermatozoid; a — eye-spot; /c — nucleus. 4, Isolated antheridia 

 liberating spermatozoids. 5, ovum surrounded by spermatozoids. 6, section through 

 a fertihsed egg; £/c=nucleus of egg; s/^/c —nucleus of sperm; s^^spermatozoids; 

 (r, 4, s after Thuret ; 2. 3 after Guignard ; 6 after Farmer.) (From Strasbuxger.) 



free as 64 motile spermatozoids, each with the characters usual for 

 the Brown Seaweeds (4). The oogonia though larger are of the same 

 pattern. Each has at hrst one nucleus ; but here it divides only 

 to form eight, and the cytoplasm undergoes cleavage into eight large 

 ova. They are also shed in the same way, and round themselves off 

 as non-motile eggs (5). 



A comparison of the antheridium with tlie oogoniuni in the Fu':aceae shows 

 that they arc ])robably results of differentiation from a common source. \M]en 

 an oogonium is to be formed, a cell of the wall of the conceptacle grows inwards 

 into the cavity, and divides to form a stalk-cell and an oOf,onium (Fig. 325, 



