92 



PRINCIPLES OP PLANT-TERATOLOGY. 



compressus "), Hincks, and Masters held that, owing 

 to the stimulus of superabundant nourishment, a 

 number of buds arise in close proximity, which, as 

 growth proceeds, exert such a mechanical pressure 

 upon each other that they become grafted together to 

 form a single shoot. It has been maintained that the 

 longitudinal striae which fasciated shoots exhibit repre- 

 sent the lines along which the presumed postgenital 

 fusion has occurred. 



b. Expansion-Theory. — The precisely opposite view, 

 fitly represented by the able writer Moquin-Tandon, 

 maintains that fasciation is due, not to the mechanical, 

 postgenital union of several separate shoots, but to 

 the flattening, i. e. to the growth-expansion in one 

 plane, of a single shoot. This view is strongly sup- 

 ported by Blaringhem who has had wide practical 

 experience of fasciation s. 



The objections raised by Moquin-Tandon against the 

 idea that fasciation is due to postgenital union of several 

 shoots have never yet been adequately met. One of 

 these was as follows : that if fasciation was due to 

 such a cause the single elliptical medullary canal which 

 is usually found on transversely cutting a fasciated 

 shoot, could never occur, but, on the contrary, two or 

 more such canals would always and inevitably be met 

 with, and one may add that the neat elliptical contour 

 of the vascular cylinder as seen in transverse section 

 of such a stem could hardly be brought about by the 

 mere 'postgenital union, however intimate, of steins ; 

 traces would always occur of the originally separate 

 cylinders. Moquin rightly further objects that it is 

 quite unlikely that a number of buds would become 

 united in one plane only. Masters says that the buds 

 are in one plane from the first. But it may be asked : 

 how and why is this the case ? Again, Moquin says 

 that in the majority of fasciated stems all the other 

 branches which should be present are to be found ; not 

 one is wanting as would have been expected had 

 fusion occurred. But a typical fasciated stem is too 



