CHAPTER V. COMPARATIVE REVIEW. ASCOMFCETES. 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 with 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 

 further special investigations how far this hypothesis can be applied to small-spored 



s 2 



