ENDOPHYLLUM SEMPERVIVI 53 
Within these ecidia the ecidiospores are produced; these 
will only infect the Juniper, on which they begin the 
cycle again. 
For all these species of Gymnosporangium the only remedy 
is to remove and burn the diseased Juniper, if it can be found ; 
if it may not be destroyed, at least the affected branches should 
be cut off, and the wounds dressed with Stockholm tar. It is 
of no use to spray or otherwise treat the Hawthorn or Pear. 
In them the disease is purely local; it comes to an end when 
the summer ends, and will not recur next year unless fresh 
infection is conveyed from the Juniper. The harm done to 
them is confined to the loss of the foliage which naturally 
weakens the tree to some extent. 
Endophyllum Sempervivi. 
THE HovuseLeEK Rust. 
This parasite attacks the common Houseleek and numerous 
other species of Sempervivum. It differs from nearly all the 
other Uredinales in having only spermatia and ecidiospores, 
the latter functioning also as teleutospores and producing basi- 
diospores. This fungus has been thoroughly investigated by 
Hoffmann (1911) from whom the following account has been 
derived. 
The ecidiospores mature on the leaves in April and May; 
they have no visible germ-pores. They germinate at once, 
while still in the ecidium; the germ-tube forces its way out 
at some point of the circumference of the spore and elongates 
to form the four-celled basidium. Each basidium produces four 
basidiospores on long sterigmata; occasionally more are pro- 
duced—Hoffmann observed as many as eight on one basidium. 
The basidiospores may be blown on to the leaf of a Houseleek 
where they germinate at once and bore through the cuticle ; 
they form a holdfast (somewhat as a uredospore does) below 
the outer wall and penetrate into the epidermal cell (see Fig. 17). 
The mycelium then branches, passes through the intercellular 
