320 



GENERAL MORPHOLOGY OF PLANTS 



uredo, having only the spermogonia and teleuto stage, as in 

 Puccinia malvaceamm, the rust of the hollyhock. 

 This diagram is for reference only: 



D 



Diagram III. Illustrating life cycle in the development of the four different form cycles 

 in the rusts. The heavy-walled oval bodies enclosing the bold face No. Ill represent the 

 primary teleutospore. The circles with the bold face No. I represent the primary secidium. 

 The circles with the short radiations or spines with bold face No. II represent the primary 

 uredp, and the lighter Nos. I, II, III in the figures represent the corresponding secondary 

 aecidium, uredo and teleutospore stages which are propagative, and thus repeat the cycle. 

 The small circle connected with the teleutospore by a short, narrow line represents the promy- 

 celia and sporidia. The narrow line issuing from the sporidium represents the mycelium 

 of the aecidial stage, the cells of which are uninucleate. The small elliptical body connected 

 with this line by a narrow, short line represents the spermogonium; the cells of this are also 

 uninucleate. The broad lines represent the mycelium produced by the germination of the 

 aecido- and uredo-spores. In reading the cycle pass from left to right. 



A represents the cycle of those species having all four spore forms. B represents the 

 cycle of those species in which the uredo stage is absent. C represents the cycle of those 

 species in which the aecidium is absent. D represents the cycle of those stages in which both 

 the secidium and uredo are absent. 



