408 



DB. M. T. MASTERS 0:X THE JTLORAL 



This arrange- 



process of development. Some of these cliauges may thus be con- 

 sidered as progressive, others as retrogressive, and not infre- 

 quently as reversions to a prior and simpler condition *. 



Oligomert. 



I. Beduction of Parts. — A dimerous condition is one of the 

 commonest deviations from the usual typical 

 structure of Orchids in general, 



ment may be thus represented, the two sepals 

 being lateral, the solitary fertile stamen A and 

 the stigma G being in the median line. This 

 dimerous condition has some indirect analogy 

 with the natural arrangement of parts in Cypri- merous Orchid. 

 pedium, where in the adult flower there are two 

 sepals only (one of these, however, resulting from the concres- 

 cence of two), and in the presence in the median line of two 

 much-modified parts, the lip and the staminode, 



P 



S A S 

 G 

 L 



Diagrammatic 

 illustration of di- 



Bract. 



s 



p 



p 



X 



ai 



a3 



G 



L 



S 



s 



Axis. 



the inner staminal whorl being represented by 

 a pair of organs placed at right angles to these, 

 and, as it were, decussating with them. 



In abnormal flowers of Cypripedium Sedeni 

 the dimerous condition is associated with the 

 presence of a single median fertile stamen in 

 the position usually occupied by the stami- 

 node X . In these cases the median sepal is 

 generally absent, whilst the two lateral ones 

 are either united or partially separated, and 

 more or less dislocated or turned to the lower 

 part of the flower. No lateral petals are 

 formed, but a petal is placed above in the 

 median line, in the position usually occupied 

 by the median sepal, and in form and colour like one of the 

 lateral petals. Opposite to this petal is placed a second one, 

 lip-like in character, or sometimes flat f. 



* A very large number of specimens have been examined by myself during 

 the last few years, and upon this examination these remarks are, for the most 

 part, based. I avail myself, however, of this opportunity of thanking Mr. 

 Hansen, of St. Alban's, for the privilege of inspecting a large number of draw- 

 ings executed by him in the rich Orchid nursery of Mr. Sander. 



t See Le Marchant Moore, in 'Journal of Botany' (1879J, vol. iviii. p. 1 ; 

 Masters, 'Vegetable Teratology/ p. 401 ; German edition, ed. Dammer (1886), 

 p. 460; Magnus, Sitzungsbericht d. Gesellsch. Naturforsch. Freunde zu Berlin, 



Diagrammatic 



illustration of ar- 

 rangement of parts 

 in Cypripedium. 



