FORKING AND FASCIATION. 



43 



same conclusions may be drawn with regard to the 

 fasciated capitulum of Garduus. Or, again, in a 

 very moist season, rapid development at the apex 

 of the root-stock of a perennial plant might induce 

 formation of a particularly vigorous shoot, which is 

 the equivalent of two or more shoots, in this sense, 

 that the tissue-matrix from which it arises within the 

 root-stock might, at the period of its development when 

 it is about to emerge as a completed bud, divide into 

 two buds producing the appearance of two shoots, 

 distinct from the beginning ; or it may not so divide, 

 and would then produce a fasciated shoot, or one with 

 a tendency thereto. 



Ring-Fasciation. — There is a second method whereby 

 individualization of the secondary heads is attained — 

 viz., by " ring-fasciation." The result of this is the 

 formation of two or more heads. The phenomenon 

 here is not quite the same as ring-fasciation in the 

 vegetative stem; in the latter it is evidently due to 

 terminal invagination of the tissues in a vertical direc- 

 tion ; in the case of the capitulum the phenomenon is 

 brought about by lateral invagination in a horizontal 

 direction, whereby the involucre reaches and occupies 

 the centre of the head while continuous with its normal 

 external portion. In some instances there may be abso- 

 lutely no sign of any such invagination, the involucre and 

 ray-florets appearing congenitally from the commence- 

 ment of the development in the centre of the disk, the 

 involucre being innermost and its bracts having their 

 dorsal side directed towards the centre, these being 

 succeeded in the outward direction by ray-florets, and 

 the disk-florets being, therefore, sandwiched all round 

 between the normally- and abnormally-placed ray- 

 florets. This phenomenon represents one stage, isolated 

 and congenitally formed, in the division of the 

 capitulum into two. The lateral invagination above- 

 mentioned represents another isolated stage. Still 

 another stage is seen, representing a more advanced 

 condition of division, where (to describe it in one of 



