278 DIVISION II. —COURSE OF DEVELOPMENT OF FUNGI. 
of aecidia, but no spermogonia. But these may be exceptional cases connected 
with parthenogenetic development, and would be no valid objection to the presence 
of sexuality as a rule, if the latter is supported by other and sufficient reasons. But 
these are at present wanting. We know of nothing in the Uredineae, which, like 
Woronin’s hypha in Xylaria, can be regarded with any probability aseven arudimentary 
archicarp, much less therefore as a distinct female sexual organ or even carpogonium. 
Yet it cannot be maintained with absolute certainty that there is no such organ, for we 
are still unacquainted with the first beginnings of the hymenium with its envelope ; there 
is a gap in the observations, and technical difficulties which are not yet overcome 
stand in the way of the completion of our knowledge. In young groups of aecidia a 
phenomenon is observed not unfrequently and without great difficulty, which seems to 
be in favour of the supposition that there is an archicarp duly equipped for conception ; 
short obtuse hyphal branches project from some of the stomata like the tips of the 
trichogyne in Polystigma (see on page 215) and may be traced here and there to a 
young perithecium. But the chief point, the continuity of such a possible trichogyne 
with the supposed archicarp on the one side and on the other its distinct relation to the 
spermatia, has not yet been shown; there is nothing in the phenomena observed which 
compels us to speak of trichogynes and not simply of branches of the mycelium which 
may as well grow outwards from a stoma as in an inward direction into an inter- 
cellular space. 
In presence of this uncertainty we cannot at present deal with the recently published 
statements of Rathay, that the spermogonia of the Uredineae allure insects to visit 
them by their fragrance which has long been known, by the saccharine contents 
of the mucilage which surrounds the spermatia, and by their colour which is often 
supplemented by the bright red or yellow tints of the part of the host where they occur, 
and thus make them involuntary agents in the dispersion of the spermatia. 
The spores, as they may be shortly termed, which are produced in the 
aecidium are mature and capable of germination from the moment that they are set 
free from the hymenium, and retain their vitality for some weeks under favourable 
circumstances. In a moist environment they put out—usually from pores previously 
formed in their wall (see page 100)—thin-walled germ-tubes which receive the proto- 
plasm of the spore-cavity together with the oily colouring matter; each spore forms 
as a rule only one tube. The next stages in the growth of the tubes and in connection 
with them the general course of development in the species exhibit in the better 
known cases two chief sets of phenomena. 
In ine first case observed only in the genus Endophyllum the germ-tube, when it 
has become about ten times longer than the diameter of the spore, ceases to lengthen 
and assumes the characters of a promycelium (see on page 111), It then 
divides at once by transverse walls, and each of the cells thus formed, generally four 
or five in number, with the exception usually of the lowest, sends out a short 
subulate lateral sterigma, and on its apex abjoints a thin-walled curved ovoid spore 
(Fig. 127). This is called a sporddium to distinguish it from other spores. Regarded 
from another connection it belongs to the category of gonidia, if the view of the nature 
of an aecidium with which we set out is the true one. The promycelium dies away 
when the sporidium has been abscised. The sporidia germinate under favourable 
conditions immediately after abscision, sending out a germ-tube which penetrates 
through an epidermal cell into the parenchyma of the proper host, and there 
developes into a mycelium which ultimately produces new spermogonia and 
aecidia. This completes the life history of the plant. 
