252 FLOWERLESS OR 



logically the pollen-grain shed by the stamens and the 

 embryo-sac of an ovule, which organs may or may not 

 be borne upon the same axis. The plants which we have 

 now to consider, with the exception of certain groups 

 of simplest structure, generally present the same phe- 

 nomenon of sexuality, manifest in the mingling together, 

 partially or wholly, of the contents of distinct cells, 

 which cells, however, or the organs to which they belong, 

 may or may not present any external or morphological 

 contrast. 



The immediate product of this mingling of the sexual 

 elements in Cryptogams varies very greatly in the different 

 groups, but it is never an embryo, with rudimentary 

 differentiation of organs, contained in a seed derived 

 from the tissues of the parent plant. 



One remarkable general difference between Phanero- 

 gamous and Cryptogamous plants consists in the pro- 

 minence in the latter of a more or less marked alternation, 

 in the cycle of development, of two distinct periods or 

 generations variously associated with methods of sexual 

 reproduction, and of an asexual multiplication by means 

 of free cells, either with or without a cellulose coat. The 

 prevalence of this asexual multiplication by free cells is 

 a further characteristic of many groups of Cryptogamous 

 plants. 



Those free cells which in their development initiate a 

 new generation, are termed spores. They consist of a 

 simple minute usually double-coated cell, containing 

 protoplasm and, it may be, starch, oil, and chlorophyll 

 besides. 



From their superficial analogy with seeds, and playing 

 also, as they do, the part of seeds in respect of the dis- 

 persion of species in many of the higher Cryptogams, the 

 spores are popularly regarded as, in some sort, parallel 

 structures with the seeds of Flowering Plants, and so 

 we find Cryptogams collectively treated of in many 

 botanical works as Acotyledonous, since, as indicated 

 above, the spores present no differentiation of organs, 

 consequently no trace of cotyledons. It will be obvious, 

 however, that the use of this term is misleading, as it 

 infers a common ground of contrast which does not 

 exist. 



