98 STUDY OF COMMON PLANTS. 



the gradual division of labor from the primitive condition 

 of affairs seen in Spirogyra, for example, in which a single 

 cell performs all the functions of the*" plant, to the pro- 

 nounced and far-reaching differentiation that has become 

 established in the higher cryptogams. 



IV. Sporophores. The spore-bearing structures that arise 

 fronr the vegetative body of cryptogamic plants are of great 

 number and variety. They include 



1. Such simple forms as the sporangiophores of the 



brown moulds or of the Peronosporeae. 



2. Compound gymnocarpous forms, of which many 



mushrooms, toadstools, etc., are examples. 



3. Compound angiocarpous forms, represented by the 



perithecia of Perisporiacese, etc. 



4. The seta and capsule of mosses and corresponding 



parts in liverworts. 



5. The leafy plant of vascular cryptogams and phanero- 



gams. 



V. Alternation of Generations. In the higher cryptogams 

 and the phanerogams the sporophore, or sporophyte, is one 

 member of a developmental cycle of which the oophyte 

 is the other, a cycle which, as stated elsewhere, is followed 

 with special readiness in the mosses, and is hardly less 

 manifest in the ferns and their allies. Besides this alter- 

 nation of sporophyte and oophyte, characteristic of all 

 groups from the mosses upwards, the study of the various 

 forms under which many fungi (the Uredinese, for example) 

 appear in the course of their development affords oppor- 

 tunity to observe some of the most remarkable phenomena 

 of plant life. For further suggestions the special litera- 

 ture must of course be consulted. See also review and 

 summary at the close of Exercise XIII. 



