THE ST KM OR SHOOT. 



95 



In the light of what is written above it would 

 seem that Plot, in his 4 Natural History of Oxford- 

 shire,' comes nearer the mark than anyone else when 

 he regards " f asciation " as due to the ascent of too 

 much nourishment for one stalk and not enough for 

 two ; though he probably ascribes too absolute an 

 influence to the external factor of nutrition. 



d. Physiological Causation. — As regards the physio- 

 logical cause of fasciation it is probably a pathological 

 condition. In the majority of cases it is doubtless 

 stimulated to appear by the presence of superabundant 

 nutrition wdiich produces a subtle diseased condition, 

 thus giving rise to a hypertrophied growth which 

 destroys the balance of the organism. 



The proof that fasciation is often due to the flow of 

 superabundant nutriment to the organ affected is 

 directly afforded by some of the experiments which 

 have from time to time been made in which artificial 

 mutilations of one part of the plant, causing a hind- 

 rance to the normal flow of sap in a particular 

 direction, have induced an over-rapid and abundant 

 flow into other unwonted channels inducing an exces- 

 sive multiplication of these channels to take the excess 

 of sap : hence the fasciated shoots. For instance Sachs 

 and also Lopriore produced at will fasciated shoots 

 in the axils of the cotyledons of the scarlet runner 

 (Phaseolus multiflorus) by excising the main axis of 

 the plumule* at an early stage; if this mutilation is 

 performed at a later stage no fasciation results. The 

 writer has repeated these experiments of Sachs and 

 Lopriore with marked success, great numbers of seed- 

 lings producing fasciated shoots in the axils of the 

 cotyledons. In every case the shoot was only affected 

 at the base, a normal growth being formed above (fig. 

 27). Blaringhem, Lopriore, and others have published 

 interesting accounts of cases of fasciation induced by 

 artificial mutilations of various kinds. 



In other cases the attacks of insects constitute the 

 cause of fasciation, and here again the phenomenon is 



