176 PRINCIPLES OP PLANT-TEEATOLOGT. 



Rolfe describes double flowers of the orchid Epiden- 

 dram vilellimim in which there were four whorls of 

 twelve petaloid organs, the two innermost being prob- 

 ably composed of stamens, all those which are 

 normally absent having reappeared ; the stigmatic 

 whorl was suppressed. 



Masters describes a flower of Gypripedium in which 

 the stamens A^, a^, a^ had the form of ordinary petals, 

 while a^ was changed into a labellum, lying immediately 

 within the normal one. Heinricher observed an extra 

 lip formed from the stamen a^ in G. Gakeolus and 

 G. Lawrencianum. 



Special attention may be drawn to the following 

 cases. Penzig mentions having seen in a great number 

 of orchid-genera the transformation of the posterior 

 stamens of the outer whorl (usually absent) into labella, 

 and attributes the labelliform character to their proxi- 

 mity to the normal labellum. But the facts about to 

 be stated do not altogether support this position. 

 Masters mentions a flower of Cypripedium Sedeni in 

 which the two median stamens A^ and a* were fertile, 

 while the four remaining ones were transformed into 

 .labella (fig. 131). The great importance of these cases 

 is noted in a previous section. The presence of these 

 supernumerary labella goes a long way in confutation 

 of the Brownian and Darwinian theory of labellum- 

 structure. 



In some double flowers of the orchid Miltonia 

 vexillaria from Baron Schroder's garden which were 

 examined, dialysis of the column had occurred, accom- 

 panied by petalody of the stamens and carpels com- 

 posing it ; the result being that on the posterior side 

 of the flower an extra number of labella and on the 

 anterior side an additional number of ordinaiy petals 

 were formed. Here we see that the type of petal was 

 determined according to whether it appeared in the 

 near neighbourhood of the labellum or of the ordinary 

 petals, Penzig's views being thus borne out by this 

 case. 



