SEXUAL REPRODUCTION. 



277 



the form of the sperm is usually that of the cell in which it 

 is produced. If it is set free, it may become globular, and 

 have slow amoeboid movements, or it may be entirely im- 

 motile. In the latter case it must depend upon the move- 

 ments of the water into which it escapes for transference to 

 the vicinity of the egg. The sperm may be ovoid and fur- 

 nished at the end with one or more cilia ; or elongated and 

 bent or coiled one or more times. The elongated forms 

 have almost invariably two to many cilia (fig. 306). 



381. The spermary. — The organ in which the sperms are 

 produced is the spermary or antheridium. It is either simple 

 or compound. A simple spermary consists of a single cell 

 whose contents is transformed into one or more sperms. 

 Simple spermaries occur only in algae and fungi, and by 

 reduction among seed-plants. (See ^f 

 385.) If more than one sperm is to be 

 formed, the nucleus, originally single, 

 becomes divided into as many parts as 

 there are to be sperms (sometimes into 

 more than become mature). The total 

 number of sperms produced by a plant is 

 related somewhat to the number of eggs, 

 but particularly to the chances of the 

 sperms reaching the egg. 



If there is but a single sperm formed 

 by each spermary, either the number of 

 spermaries is great or some adaptation 

 exists for the certain transfer of the sperm 

 to the egg. In Cystopus and its allies, 

 for instance, a branch of the spermary 

 grows into the ovary, through which the 

 sperm passes to the egg (fig. 307). 



A simple spermary arises either by the differentiation of 

 one of the ordinary cells, or of a special lateral branch, as in 



Fig. 307.— The sex organs 

 of Peronosfiora. h, 

 hypha which has devel- 

 oped at the end the 

 ovary, o, containing a 

 single egg (the central 

 dark sphere^, h' , hypha 

 which has developed the 

 spermary, n, whose pro- 

 toplasm, constituting a 

 single sperm, is passing 

 through the fertilizing 

 tube (a branch of the 

 spermary) into the egg. 

 Magnified 350 diam. — 

 After DeBary. 



