II. 



PARASITIC FUXGI: THEIR MODE OF ATTACK AXD THE 

 MEANS OF ITS PREVENTION. 



By George Massee, F.L.S., F.R.M.S. 



Abstract of a Lecture delivered at Watford, l^th November, 1895. 



Although the subject of Parasitic Fungi is one upon which I have 

 delivered several discourses, I am bound to confess that every one 

 of them has been a signal failure from the point of view of certain 

 members of my audience, who expected to have details of their own 

 grievances and to hear of remedies for the particular ailments of 

 their own plants. If anyone has come here this evening with that 

 idea they will be disappointed, for my object is not to treat of the 

 particular cases of injury inflicted by certain species of Fungi, but 

 to give a general idea of their work and nature, and of the broad 

 principles which should guide us in our attempts to prevent them 

 from doing injury. 



The life-history of the higher plants is simple compared with 

 that of these lowly organisms. When one of their seeds germi- 

 nates a plant springs up which is like the one from which the seed 

 was procured. When, for instance, a chestnut or a beech-nut is 

 planted and germinates, there is recognized from the first some- 

 thing growing as a chestnut or beech-tree, as the case may be, 

 which as time goes on will bear fruit similar to that from which 

 it springs. It is not so with Fungi. At one time they look like 

 one specific thing, and at another phase of their life-history they 

 appear to be something totally different, so different indeed that 

 until their history had been traced they were classified as belonging 

 to different groups. In the present day we can afford to laugh at 

 such mistakes when we find ttem in old books, but it is by the 

 work of the older writers that we are now able to prove step by 

 step that several of the different forms with which we are familiar 

 often belong to on^ and the same organism. 



Differences in Fungi often arise from what they grow upon. If 

 the spores of one kind of fungus, or even of one individual plant, 

 be taken and sown upon different kinds of food-material, they may 

 give rise to what appear to be totally different things. Low down 

 in plant-life, as well as in animal-life, it has been found that forms 

 are fairly elastic, not almost rigidly alike, as each species usually 

 is in the higher forms of life. There is in them a certain amount 

 of elasticity which enables them to present themselves under 

 different appearances and to do different work, depending on the 

 circumstances under which they are placed. For instance, common 

 yeast, with which we are all familiar, under different circum- 

 stances assumes different forms, the internal machinery adapting 

 itself to the work which has to be done, the fungus in one case 

 producing alcohol, and in another sugar, with no alcohol at all, 

 and, if examined under the microscope, looking totally different. 



