58 



BOTANICAL GAZETTE 



[JANUARY 



I hope that it may be clear that the shoot-and-sporophyll theory 

 is not here called in question, but only the use of teratological forma- 

 tions as competent evidence. The ground is taken that these 

 formations do not remove all doubt as to the origin of the fertile 

 scale, but on the contrary only after all doubt has been removed as 

 to the nature of the scale, by legitimate argument from comparison 

 of normal structures, do the monstrous formations begin to have any 

 considerable historical significance. 



2. Homoeosis has played a part — necessarily from its nature, 

 which is essentially anarchical, a small part — in the evolution of 



plants. 



m 



We can trace to a 

 e o t i c origin certain 

 established sequences in de- 

 velopment, of which specific 

 examples may be adduced. 



(a) Habenaria quinqueseta 

 (or Michauxii) of the southern 

 states carries on vegetative 

 reproduction by certain of its 

 roots. At the apex of these 

 roots, close to the punctum 

 vegetationis , pointing back- 

 ward in the embryonic tissues, 

 a stem apex is organ 



ized. 



root 



Fig. 16.— Median longitudinal section of 



represented, the root-apex 



Fig. 16 shows its relations to 

 the apical regions of the root. 

 Two leaves and a bud in the 

 axil of one of them have 

 already been differentiated. 

 Subsequently to the stage here 



forms 



new shoot a spherical tuberoid growth evidently with storage 



functions. 



As to the evolution of a shoot fundament in this curious position, 

 one, I suppose, will imagine that thp or,*;™ ^..riAMn hictorv 



conn 



the 



