Feb. IS, 191S 



Brachysm 395 



branches that often accompany brachytic variations and are of very 

 frequent occurrence in cluster varieties. Fasciation, or duplication of 

 parts, appears in many different stages, ranging from simple forking of 

 intemodes or pedicels to inclusion of two flowers in the same involucre, 

 or two bolls in the same calyx, or to an abnormal increase of the number 

 of carpels.' 



Sometimes the fasciated intemodes remain united for their whole 

 length and bear two leaves at the end, like the intemodes of opposite- 

 leaved plants. In rare cases double intemodes bear two flowers or bolls, 

 though usually the floral buds of abdominal intemodes are aborted. (See 

 PI. LIX.) 



Union between the pedicel of a boll and the next intemode of the fruit- 

 ing branch is another abnormality to which reference has already been 

 made. Adhesion occurs in connection with brachysm, though it also 

 appears occasionally in connection with short joints in noncluster varieties. 

 It is more likely to be noticed in such cases because of the contrast with 

 the normal joints of the branch. Doubtless as a result of the fact that 

 the pedicel of the floral bud develops normally in advance of the next 

 joint of the branch, these adherent intemodes are bent upward in the 

 direction of the pedicels to which they are joined and form a distinct 

 angle or elbow with the preceding intemode of the branch. (See PI. LX.) 

 It is evident in such cases that the abnormality involves something more 

 than a mere adhesion of the epidermal tissues, for the affected intemodes 

 are much shorter than the others, and even shorter than the pedicel to 

 which they are united. In most cases the short joints lose their floral 

 buds or young bolls by abortion. 



ANALOGY BETWEEN BRACHYTIC VARIATIONS .\ND HYBRIDS 



The fact that the shortening of the intemodes is so often accompanied 

 by abnormal leaves and involucres suggested the view here advanced, 

 that brachysm represents a failure to maintain the normal specializa- 

 tions of the parts. Considered as examples of intermediate expression 

 of characters, the shortened intemodes and abnormal involucres of the 

 cluster cottons afford a suggestive analogy with the abnormal interme- 

 diate forms of branches and involucres that often appear in hybrids 

 between diverse species of cotton. This analogy may be supported by 

 the fact that sterility, or blasting of the buds or the young bolls, is very 

 frequent in brachytic varieties of cotton, as well as in hybrids, and is 

 especially common in involucres that liavc the abnormal intermediate 

 forms of bracts. 



The idea that short-jointed variations differ from the parent stocks 

 in only this one character, as often assumed by writers on Mendclism, is 



1 Reasons for looking upon fasciation as a s>'raptom of defeneration have been given by Thomas Mcehau. 

 (Science, v. 3. no. 70, p. 694. 18S4.) Meehan concluded that "a fasciated branch is an imperfect and pre- 

 cocious attempt to enter on the flowerine or reproductive staRC." 



