304 H. MARSHALL WARD. 



transmitted its effects through countless generations to the 

 individual plants of Char a cr in it a which now reproduce with- 

 out any sexual act at all. And the same is true for other 

 cases. 



There is one fact apparently universal in sexual reproduction ; 

 it does not take place until a large quantity of material is 

 either accumulated, or is in some way placed at the disposal of 

 the sexual organs. If these sexual organs are to be looked upon 

 as specialised to secrete the sexual elements, or to sort the 

 substances of which they consist^ as it were^ this may be of 

 importance. 



It must be allowed that no satisfactory theory exists, how- 

 ever^ to account for the gradual disappearance^ 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. 



The sexual act, however, consisting simply or mainly in the 

 re-invigoration of protoplasm by the addition of protoplasm of 

 a different nature (though we do not know the kind or limit of 

 difference) from a distance, it may be that an explanation of 

 what occurs in the Fungi is afforded by their mode of life. I 

 have already pointed out that the Fungi in which sexual organs 

 seem to be most certainly absent are those which are most 

 highly specialised as parasites. Now, we have every reason to 

 believe, first that parasitism is a matter of degree, and secondly 

 that the most highly specialised form of parasitism consists in 

 directly obtaining those contents of the cells of the host which 

 are chemically most complex, and therefore contain most 

 energy. 



I need not dwell on the degrees of parasitism exemplified by 

 plants which merely rob their hosts of space or moisture, or 

 which have obtained a hold so intimate that they break it up 

 and feed on the rotting debris, but may at once pass on to 

 consider a few consequences which follow from the mode of 

 life of those highly specialised parasites which have become so 

 closely adapted to their host, that they exist for a time as all 

 but an organic part of its tissues and substance. 



