BACTERIA. FUNGI. 165 
proportion as the one end elongates the other dies away. Hence the same effect is 
produced as if the progressive motion of these hyphz were like that of ship-worms. 
This impression is particularly strong in cases wherein one part of the mass of 
wood attacked exhibits hyphz occupied with their mining operations and growing 
through partition walls, whilst the other part has been the scene of past activity, 
and exhibits numbers of drilled holes, but no longer any trace of hyphz. The fact 
that a plant is thus invaded internally by the parasitic mycelia of fungi is not 
always betrayed by its external appearance. Sometimes the hosts remain somewhat 
backward in development, but this circumstance might be just as well due to other 
causes, perhaps to unsuitability of situation. It is not till the mycelia need once 
1p 
Fig. 32.—Hyphe of Parasitic Fungi. 
1 Of one of the Peronosporew, 2 Of a Mildew. 3 Of one of the Polyporex. 
more to multiply and distribute their kind that they emerge partially from the 
host; they then lift their spore-forming hyph above the surface, leaving it to the 
wind to distribute the spores as they are detached. 
This process vividly recalls the similar behaviour of those water-plants which, 
in a similar manner, vegetate submerged for months, and only come to the surface 
at the flowering and fruiting seasons, in order to expose their flowers to insects, 
and their seeds to the breeze. We are also reminded of the saprophytic orchids 
already described, which nourish themselves and grow for years imbedded in the 
humus of woods, and then seize the opportunity afforded by a favourable summer 
to raise up in a few weeks flowering stems above the bed of the forest. As a rule 
the spore-bearing hyphe, emerging from the hosts of parasitie fungi, are highly 
conspicuous both in form and colour. As well-known instances we may here 
mention the powdery, rust-coloured, chocolate-brown, or coal-black masses of spores, 
known by the names of rust and smut; the mealy, orange-coloured masses which 
make their appearance on the green stems and fruits of roses (Aicidium stage of 
Phragmidiwm subcortiewm), and the discomycetous Peziza Willkommir, which 
is parasitic in the branches of green larches, and exposes its fructifications beyond 
