58 H. MARSHALL WARD. 



sluggish mass of protoplasm, by the addition of another and different 

 mass of protoplasm. That an advantage is often attained by the latter 

 mass coming from a distant source, is sufficiently evident from what 

 we know of cross fertilisation generally. 



It now remains to be seen if we can throw any light on the curious 

 disappearance of sexual organs and sexuality in the fungi — curious, 

 because the sexual process appears to be all but universal in all organ- 

 isms excepting the very lowest. 



A hypothesis which suggests itself, and which Eidam favours, and 

 which is certainly supported by some analogies, is to the effect that 

 the apogamous fungi are not- always apogamous. "We know that many 

 forms only produce their sexual organs at comparatively long and rare 

 intervals. The Mucors, 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. 



Accepting that the sexual process consists essentially in a re-invigo- 

 ration of the protoplasm of the organism, may it not be that one sexual 

 act is effective through long periods and many generations 1 Such a 

 view is supported by the known cases of parthenogenesis in other 

 plants, and would explain such cases as the Saprolegnice, if it were 

 placed beyond doubt that protoplasm does occasionally pass through 

 the "fertilising tubes" to the oospheres. 



Moreover, the cases of polyembryony — where several embryos arise 

 in an embryo sac, although only one oosphere is fertilised — favour the 

 view that the effect of fertilisation may be extensive ; and we cannot 

 doubt that such is the case where adventitious covering branches arise 

 after the conjugation of certain Mucorini {e.g. M ' ortierella), and in the 

 Orchidece, where fertilisation or even the mere growth of the pollen 

 tube affects the whole flower. 



In other cases, however, great difficulties are experienced. It is 

 not easy to conceive how fertilisation in a distant past has transmitted 

 its effects through countless generations to the individual plants of 

 Chara crinita which now reproduce without 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 accumu- 

 lated 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 



