CHAPTER V.—COMPARATIVE REVIEW.—ASCOMPFCETES. 259 
and spermogonia with those first mentioned is indubitable ; but, on the other hand, we 
know nothing certain in almost all these latter cases about the function of the 
spermatia. We may certainly assume that they are male fertilising organs in all the 
species which possess an organ (trichogyne or ascogonium) which may be intended to 
be fertilised. The swelling too of the spermatia in a nutrient solution, or even the 
extrusion of a germ-tube, would not be an objection to this assumption, since 
processes of growth might make their appearance, as Stahl has already remarked, in 
this mode of cultivation, which in the natural course of development would only be 
set up after contact with the organ to be fertilised, just as pollen-tubes are formed in 
saccharine solutions. But, as was shown above, the female organs to be perhaps 
fertilised are actually known only in a comparatively small number of species, and in 
the rest, which are the large majority, the functions of the spermatia must therefore be 
declared to be doubtful. If we suppose them to occur in species which have no 
female organ, they cannot there have a sexual function. Yet we can hardly call them 
rudimentary organs; and the enormous numbers in which they are produced are 
opposed to the view that they are entirely without function: their function therefore 
remains for the present undetermined. 
Supposing after what has now been said that we have satisfied ourselves as to 
the distinction between spermatia and small spores, and as to the mode of naming 
them and their receptacles and so on, and can find our way in the practical description 
of them, an interesting subject of enquiry still remains in the homological relations 
between the two kinds of organs, for there is a striking agreement between them, not 
only in form and structure, but also in that which is of much greater importance, 
namely, the place or moment of their appearance in the course of the development. 
In the latter respect, for instance, the commencing small-spored pycnidium of 
Cucurbitaria Laburni agrees with the spermogonium of Polystigma or Physma. 
Here we may say, without exaggeration, that the only difference lies in the germination. 
In this and similar cases we only know the first products of germination, the germ- 
tubes; we do not know what is developed from them. We might therefore consider 
them to be formations which are incapable of further development, like the pollen- 
tubes in a saccharine solution, or we might at least enquire if they are not of this 
nature. However, we may put this point out of consideration and assume that 
they are in all cases capable of producing a mycelium. This assumption does 
not prevent us from maintaining their homology with true spermatia. On the 
contrary, we may very well conceive that we are dealing witn homologues of different 
adaptation or metamorphosis, and this different adaptation would arise in correlation 
with the absence of the female organ capable of fertilisation; for, as far as we 
can see at present, the phenomenon in question occurs exactly in those forms 
which have no female organs, having lost them probably in the course of the phylo- 
genetic development, as we have already endeavoured to show. It is no sufficient 
objection that this metamorphosis of the spermatia is not found in all species that 
have experienced this loss, for phenomena of this kind vary continually from species 
to species. 
The hypothesis that there are such metamorphosed spermatia would make many 
facts more intelligible than they have hitherto been. It will depend on the results of 
farther special investigations how far this hypothesis can be applied to small-spored 
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