50 The Field Naturalist's Quarterly Feb. 



some and untidy method, and unnecessary when we have 

 a micro-section to examine corresponding to the dried leaf 

 on the card. 



The cards can be arranged in families and kept in en- 

 velopes with the name of the genus or species written 

 outside. 



The Spores. — " By their fruits ye shall know them " is an 

 ancient dictum that applies with especial force to the groups 

 of plants under consideration. In higher groups of plants, 

 such as Carex, we know that it is often impossible to deter- 

 mine a species unless we have the mature seeds to examine. 

 But, happily for the student of the Sedges, each species has 

 but one kind of seed. In the Uredinece, however, species 

 have one, two, or three kinds of seeds or spores produced in 

 regular sequence from the same mycelium in an alternation 

 of generations. To this remarkable state of things Dr M. C. 

 Cooke has given the rather awkward name of dichocarpism. 



The mycelium of a fungus is its vegetative system, and cor- 

 responds partly to the roots of higher forms of plant life. 



Dr C. B. Plowright thus tabulates the spore-relations : — 



Promycelial Spore. 



Teleutospore. Uredospore. Spermogonium. Spermogonium. 

 Teleutospore. Uredospore. ^icidiospore. 



Teleutospore. Uredospore. 



Teleutospore. 



Not only are there these several phases of existence that 

 make up the life-history of a species, but many of them are 

 hetercecious in addition — i.e., part of their life is spent on one 

 host-plant and the other part is completed upon a host-plant 

 of quite another order; ex. gr., Puccinia caricis in April pro- 

 duces spermogonia upon the Nettle, Urtica dioica. These 

 spermogonia are minute papules formed upon the veins of a 

 leaf or upon the stem. When mature they rupture at the 

 apex and disclose fine threads surmounted by spore-like sper- 

 matid embedded in a glutinous material that swells with 

 moisture. Shortly afterwards are formed the well-known 

 Cluster-cups or JEcidia. Under a simple lens these are seen 

 to be a multitude of beautiful little yellow cups with torn 

 edges, looking like the petals of a flower, and they contain 



