CYSTOPU>S, OR WHITE RUST. 149 



We need not consider here the suggestion of De Bary that 

 profound chemical differences exist and effect the environment, or 

 Sach's recently expressed view as to the analogies between ferment 

 actions and fertilisation. Enough for our purpose that sexual 

 reproduction essentially consists in the reinvigoration of a slug- 

 gish mass of protoplasm, by the addition of another and 

 different mass of protoplasm. It must be allowed that no 

 satisfactory theory exists to account for the gradual disappear- 

 ance, first of sexuality, and then of even the morphologically 

 represented sexual organs in the Fungi ; and any attempt to 

 explain the matter seems to involve more than one vicious 

 assumption. It has been suggested by Eidam and others that 

 the apogamous Fungi are not always apogamous. The Mucors, 

 or Moulds, for instance, may be propagated through numerous 

 generations by means of the asexual spores ; the sexual organs 

 only arising now and again under favourable conditions. But 

 it is not easy to conceive how fertilisation in a distant past has 

 transmitted its effect through countless generations to the individ- 

 ual plants which now reproduce without any sexual act at all. 



Now, reverting to the subject of parasitism, it can scarcely 

 be doubted that the protoplasm of a higher plant, such as a 

 phanerogam, differs from that of a lower cryptogam in being 

 capable of doing more work ; and that the great advantage 

 derived by a parasitic Fungus which has its life so adapted that it 

 can tax the cells of a planerogamous host-plant, is, that it obtains 

 its food-materials in a condition more nearly approaching that of 

 its own substance, than would be the case if it had to work these 

 materials up from inorganic matters. Now, it seems not impro- 

 bable that the protoplasm of a phanerogam may contain so much 

 energy that it can not only supply the vegetative mycelium of a 

 parasitic fungus with all that it requires for its inmiediate growth, 

 but also suffices to enable that fungus to store up enough energy 

 in its asexual spores to last until the next generation of the fungus 

 gains its hold-fast on another source of life-giving substance. But 

 we may imagine even this to fail after a time, and that at length 

 the fungus derives too little benefit to be able to go on, or tliat 

 the season during which the host-plant flourishes is drawing to an 

 end. 



