2 1 8 Marshall Ward . — -Illustrations of the Structure 
longitudinal section : it is already discoloured. Further 
details are not shown. In the intercellular spaces of 
the right-hand moiety of the figure are the fine septate 
branching hyphae of the fungus, and these are giving rise 
beneath the epidermis to the first series of spores, known as 
uredo spores ; all stages of development being shown, as the 
uredospores force up the epidermis, rupture it, and appear 
on the surface as the rusty streaks so hated by the farmer. 
(Zeiss B.) 
In Fig, 2 are seen the details of development of the uredo- 
spores under a higher power. Separate branches of the 
septate mycelium (which contains protoplasm with scattered, 
oily, orange-red drops) ascend and become swollen at the tip : 
the tip becomes full of very dense, fine-grained protoplasm, 
and a septum is formed across below the swelling. The 
swelling enlarges, and its oil-like orange-coloured contents 
increase in amount : the cell-wall thickens also, and a pale 
central nucleus-like body is seen at a certain stage. Further 
enlargement follows, the orange contents increase in amount 
and in depth of colour, and the cell-wall becomes thicker : 
then regular spike-like projections are formed on the outside 
of the thickened cell-wall. When the spore is completely 
developed, as in the larger specimen above, the wall is 
found to be divisible into at least two evident layers, a thick 
outer exosporium , which is in its turn stratified into at 
least two layers, and a very thin endosporimn. The spore 
is ellipsoidal in form, and has three or four rather large 
germ-pores at equal distances apart on a zone midway 
between the two ends : the germ-pores are really pits — thin 
circular depressions in the inner part of the endosporium 
and exosporium, and they serve for the emergence of the 
germ-tubes . Occasionally there is a thin place at the end 
where the spore isjoined to the stalk. (Zeiss E.) 
Fig. 3 shows a series of four successive stages in the ger- 
mination of the same uredospore, sown in water on glass. In 
a are seen two germ-tubes, emerging from opposite germ- 
pores ; b , several hours later ; c ) later still. It will be noticed 
