REPROD UCTION. 1 89 



to exist as far as that particular generation is concerned, as. for 

 example, during the winter, or during periods of dryness. 

 These spores (" resting-spores ") usually develop at the next 

 period of vegetation (spring, rainy season). On the other hand 

 some spores develop soon after their maturation. They are 

 usually endowed with a delicate membrane, as distinguished from 

 the resting-spores, which have a more firm, usually colored, mem- 

 brane. Such are the u swarm-spores, " so called because they 

 can move about in the water until they prepare themselves for 

 germination. As soon as they are ready to develop they come to 

 rest or fasten themselves in some suitable place. (Algae and some 

 fungi.) Sexual reproduction is not known to occur in all crypto- 

 gams ; many investigators now agree with BREFELD that it does 

 not occur among fungi. 1 Among the remaining cryptogamic 

 groups algse (at least the great majority), mosses, and vascular 

 cryptogams sexual reproduction undoubtedly occurs. The anther- 

 ids are the male sexual organs (among cryptogams); they contain 

 the fertilizing elements, the spermatozoids. The oogonidia, (egg- 

 receptacle), or, when more complicated in structure, the archegonia y 

 are the female sexual organs ; they contain the egg-cell. 



The spermatozoids are either very minute oval cells or, among 

 the more highly differentiated cryptogams, spiral threads. These 

 threads are usually supplied with two cilia (organs of motion) at 

 the thinner anterior end ; the other end, which is usually thicker, 

 contains plasm. The basal substance of spermatozoids (hence 

 exclusive of cilia), according to more recent investigations (SCHMITZ, 

 STRASBURGER, ZACHARIAS), consists of ' ( nuclein, ' ' that is, nuclear 

 substance. 



The oogonium contains the egg-cell. In its simplest form the 

 oogonium consists only of a covering for the egg-cell. The egg- 

 cell is frequently enclosed in a special organ known as the arche- 

 gonium ; in its form it usually resembles an Indian club of variable 

 length. In the archegonia of mosses and vascular cryptogams one 

 may recognize a shorter or longer " neck " and an enlarged base 

 (venter) containing the egg-cell. The figures will assist in illus- 

 trating and explaining what has just been stated. They refer to 

 algse, mosses, and vascular cryptogams. Fig. 110 illustrates the 



1 Perhaps also true of lichens ; as already stated, STAHL's observations have not 

 been verified. TRANS. 



