GERMINATION OF BASIDIOSPORES 15 
If one of these easily detached basidiospores or conidia is 
conveyed to the surface of a leaf or young stem of Nettle, its 
germ-tube bores through the cuticle 
and enters the tissues (Fig. 17), 
where it ramifies and forms a my- 
celium. The teleutospore is large 
and heavy, and firmly attached to 
its spore-bed on the leaf of Carex; 
the basidiospores enable its con- 
tents to be transferred easily to Fig 17. Endophyllum Sem- 
pervivi. Germinating basi- 
the surface on which alone they diospores (after Hoffmann) ; 
are capable of further growth. But —%,,tbe spore: ® the germ. 
. i ‘ ‘ vesicle, under the cuticle of 
their wall is thin and they can live _ the epidermis; a, b, c, show 
only for a short time; they contain bea care Sa oe Seecinley 
but little food-supply and could not —-* about 200. 
form a long germ-tube. That is the reason why their germ- 
tubes do not, like those of the other spores, search for a stoma, 
but enter by the quickest means. Nevertheless they can 
abnormally enter by a stoma; De Bary records such a case in 
his account of P. Dianthi (see Fig. 24). 
The germination of the teleutospores of P. Caricis takes 
place about the second week in April, and on the mycelium 
produced by the basidiospores in the nettle there arise, in 
about a fortnight, first spermogones and then ecidia like those 
with which we started. But the mycelium arising from the 
basidiospores does not always proceed immediately to spore- 
production. In some species, e.g. Endophyllum Sempervint, it 
hibernates in the growing point of the shoot, or in the leaves 
if they are evergreen, as in Puccinia Bust, or in the stems or 
branches in the case of some that live on shrubs or trees, as in 
Cronartium ribicola. 
Rather more than a twelfth of the species of Uredinales are 
now known to be hetercscious. This mode of life may be 
regarded partly as a device by which the parasite tides over 
the time during which one of the host-plants is not available. 
The leaves of the Nettle are delicate and soon perish in the 
autumn; those of the Sedge persist throughout the winter. 
The power of hetercecism increases the ability of the fungus to 
