298 H. MARSHALL WARD. 



placing them in strong contrast to such as Ascobolus (accord- 

 ing to Janckweski's researches), unless intermediate forms 

 like Pyrouema and the saprophytic Pezizas are compared 

 also. 



Enough has now been said to show that there is at least 

 strong reason for believing that a connection exists between 

 the mode of life of a given Fungus and the extent to which it is 

 apogamous. It will no doubt be suggested that there are still 

 cases where this view seems at variance with the facts. With- 

 out wishing in any way to strain matters at this point, it may 

 be noted that we really know very little of the mode of life of 

 very many Fungi, and that the terms saprophyte and parasite 

 are used somewhat loosely. This being admitted, it may 

 happen that further knowledge will strengthen the connection 

 spoken of. 



We are at least assured that profound dijQTerences exist — in 

 degree, at any rate — between the saprophytism of a Mucor 

 growing in a solution of horse-dung, and of a Pythium de- 

 veloping its fructification in the rotting parenchyma of a plant 

 which it has previously killed. 



There is also an equally striking difference between the para- 

 sitism of an epiphyte like Erysiphe and that of a highly- 

 specialised iEcidiomycete like Puccini a. But I would insist 

 upon more than this. It is not only in the mode of attacking or 

 living upon the substratum that one fungus differs from another ; 

 differences as to the kinds and quantities of the various matters 

 absorbed must also exist, and a Uredine in a leaf no doubt 

 obtains different food (and in a different way) from that taken by 

 Claviceps in a grain of rye, or Us til ago in a hypertrophied 

 swollen stem of Zea Mays. That these differences may be 

 very important — though we do not know exactly in what they 

 consist — is fully demonstrated in cases of heteroecism. 



I have already pointed out that the coexistence of apogamy 

 (or the total suppression of sexual organs) and parasitism is 

 noticeable especially in the highly specialised parasites. In 

 forms which, like the majority of the parasitic Perouosporese 

 and Zygomycetes (e.g. Pep tocephal is), are nevertheless 



