362 MELAMPSORELLA 
witches’-brooms on the Fir, the infected buds producing dense clusters of 
small leaves which are not.pseudo-distichous (as in the normal shoots) but 
spirally arranged, moreover they are not evergreen, but fall off in August, 
On these leaves the spermogones and excidia are seen in June; and the 
zcidiospores infect the second host and produce uredo-sori in 10—14 days. 
It will be seen that the teleutospores found in spring do not belong to the 
same generation as the uredospores found in the following summer. 
The mycelium of both stages is perennial, so long as the host survives, 
this being the only known instance of such a state of things ; for this 
reason the parasite can maintain itself on either the Fir or the other host 
quite independently. On the Fir, it produces in time large cankerous 
growths. There is some evidence that a specialisation into biological 
races on different species of Alsinee has begun. In the latter the 
On 008 
©, 28 ot So% B2 
° 
a 
o 
° 
\g 
Fig. 270. M. Caryophyllacearum. a, cells of the peridium of a uredo-sorus, 
on Stellaria graminea, showing the opening pore being formed beneath a 
stoma, seen through the epidermis, x 600; b, an epidermal cell of S. 
nemorum, containing teleutospores (after Fischer) x about 400 ; c, attacked 
leaf of S. graminea, slightly enlarged; d, one young and two mature 
uredospores, x 600. 
mycelium grows up with the young shoots and gradually spreads upwards 
into every leaf, making the leaves in many cases smaller, but not much 
different in colour. I have seen a few uredo-sori on the upper side of the 
leaves, and even on the sepals of Cerastium. 
The peridium of the uredospores is formed of a definite hemispherical 
pseudo-parenchymatous layer, one cell thick, most of the cells being 
polygonal by mutual pressure, nearly smooth, and containing at first a 
little of the same yellow oil as the uredospores. It bears a very close 
resemblance in texture to that round the uredo-sori of Pucedniastrum 
Circaeae, Milesina Blechni, Uredinopsis filicina, and their allies. 
The heterecism of this parasite was established by Fischer in 1901 
(Zeitschr. f. Pflanzenkr. xi. 321) ; the result was attained only after a long 
