CONCRESCENCE AND ARREST 51 



would naturally expect that a lateral shoot removed from the shoot- 

 system and planted vertically and which rooted would behave similarly. 

 We must however bear in mind that in the cutting nutritive relationships 

 obtain other than those occurring in the lateral shoot attached to the 

 tree from which the chief shoot has been removed. The whole root- 

 system of the plant, and all the existing food-material in it, stands at 

 the disposal of the attached lateral shoot, which becomes the chief 

 shoot through stronger nutrition. The rooting of cuttings of Coniferae 

 is relatively feeble, and in proportion to this stands the nutritive activity 

 which cannot overcome peculiarities imprinted on the twig, that is to 

 say, its disposition ; as a consequence branch-cuttings of the fir form 

 chief axes only with difficulty. I have seen the leaf-like distichously- 

 leaved branches of Phyllanthus lathyroides grow up as cuttings to many 

 times the length which they reach on the parent plant ; they were not 

 radial, although at their base radial shoots developed. 



V. 



CONCRESCENCE AND ARREST. 



The investigation of the formation of organs at the vegetative point 

 frequently does not suffice for the recognition of homologies, because 

 these are often concealed 

 through occurrences which 

 can be elucidated only by 

 comparison with other 

 forms. 



Let us assume, for 

 example, that the flower- 

 organs which are repre- 

 sented to the left of 

 Fig. 2i l belonged to an 



FIG. 21. Scirpodendron costatum. Figure to left : transverse section 

 of a three-flowered spikelet. Figure to right : diagram of same. ffa.x\s 

 of inflorescence with bract opposite, /primary flower in axil of bract, a 

 ISOlated mOIlOCOtyledOn- an d ^ prop hylls in axils of which arise secondary flowers // and ///. 



ous plant whose stamens 



occurred only in the number and with the arrangement shown. Every one 

 would say we have here an axillary male flower with only one perianth- 

 leaf; as a matter of fact however there are three male flowers, each of 

 them being reduced to a single stamen, and the perianth-like leaf is not 



1 See Goebel, Uber den Ban der Ahrchen und Bliiten einiger iavanischen Cyperaceen, in Ann. du 

 Jardin Bot. de Buitenzorg, vii. 



E '2 



