78 BOTANY 



This parasite specially attacks clover, but heather, 

 gorse, and other hard forms are not exempted from it. 

 And while it does not produce pathological growths in 

 its host, it simply sucks out its nourishment until it is 

 destroyed and great patches of the host plant are killed. 



Hardly to be considered actual disease, there are 

 still other abnormal phases of growth of which mention 

 should be made here, and they are the growing together 

 of series of stems, or several leaves and stems or other 

 parts to form a broad irregular structure. This is called 

 u fasciation," and the tendency to produce it seems to 

 be inherited. The hypertrophy of some organs and 

 numerous other irregular departures of growth may 

 affect plants as well as animals. Many of these are of 

 special interest to the morphologist, for these " sports " 

 have sometimes given the clue to the explanations 

 desired regarding the interpretation of normal structures. 



In every phase of this work, as in all other branches 

 of modern science, large numbers of data have to be 

 collected, tabulated, and correlated, and the resulting 

 deductions tested by experiment. When the import- 

 ance of agriculture and forestry are fully recognised, 

 we may expect to see plant doctors and health inspectors 

 augmenting the comparatively small number who to- 

 day concern themselves with plant diseases. 



