188 COMPENDIUM OF GENERAL BOTANY. 



selves the factors of reproduction are utilized in establishing 

 classes, orders, and genera. From this we may draw the conclu- 

 sion that in a book like the one before us, in which taxonomy is 

 not more fully treated, the special chapters on reproduction must 

 also give a general concept of the systematic arrangement of 

 plants. 



I. EEPRODUCTION AMONG CKYPOTGAMS. 



We will speak first of the reproduction of cryptogams in gen- 

 eral as compared with that of phanerogams. Generally the seeds 

 of cryptogams are called spores ; they usually consist of one or of 

 & few cells and are mostly microscopic in size. In contradistinc- 

 tion thereto the seeds of phanerogams are larger and of a more 

 complicated structure ; they consist of several parts. The perfect 

 phanerogamic embryo within the seed-coverings has essentially the 

 structure of a bud. 



Very frequently the spores of cryptogams are formed by asexual 

 methods, and not as the result of fertilization. (SACHS ' proposed 

 the term conidia ["gonidia"] for all thallophyte-spores produced 

 asexually; EICHLER,' using the same term, applied it to the asexual 

 motionless spores of fungi ; while WARMING wishes the term applied 

 only to the asexual thallophyte-spores produced exogenously. It 

 would no doubt be appropriate to follow the proposition of SACHS. 3 ) 

 The seeds of phanerogams are, however the direct product of 

 fertilization. 



There is also a series of cryptogamic spores which are the imme- 

 diate product of two cells reacting upon each other. These spores 

 are called oospores (egg-spores) when the two cells reacting upon 

 each other are externally very different ; zygospores (zygotes) when 

 the uniting cells seem to be entirely or almost entirely alike : the 

 latter process is called conjugation. 



Most spores pass through a period of rest (resting- stage). 

 With the maturation of the spores the plant for a time ceases 



1 Compare GOBEL'S Grundzuge der Systematik. 



2 Syllabus, 1886. 



3 The term spores is, in general, also applicable to the reproductive organs of 

 the so-called " higher " cryptogams mosses and vascular cryptogams ; they are 

 also produced asexually. 



