240 HOMOLOGIES OF THE CuAr. VIII 



all were observed excepting a^, which is the most 

 diflScult one to trace, and apparently is oftenest absent. 

 In the Cypripedese, again, all were traced except Us* 

 which, I feel pretty sure, was here really absent : in 

 this tribe the stamen (AJ is represented by a con- 

 spicuous shield-like rudiment, and «! and a^ an; 

 developed into two fertile anthers. In the Ophrese 

 and Neotteae all were traced, with the important 

 exception of the vessels belonging to the three stamens 

 ((Xi, aj, and Us) of the inner whorl. In Gephalanthera 

 grandiflora, I clearly saw a^ proceeding from the 

 anterior ovarian group, and running up the front of 

 the column. This anomalous Orchid has no rostellum, 

 and the vessel marked S, in the diagram was entirely 

 absent, though seen in every other species. 



Although the two anthers {a^ and aj of the inner 

 whorl are not fully and normally developed in any 

 Orchid, excepting Cypripedium, their rudiments are 

 generally present and are often utilised ; for they often 

 form the membranous sides of the cup-like clinandrum 

 on the summit of the column, which includes and pro- 

 tects the pollen-masses. These rudiments thus aid 

 their fertile brother-anther. In the young flower-bud 



siipplyins; the fertile anther runs tion of a frea filament in front oJ 



up the connective membrane be- the labellum, ns in the case of 



tween the two anther-cells, but Glossodia before mentioned ; and 



does not bifurcate : the ves el to this will perhaps a'-count for ths 



the rostellum runs up to the top absence of spiral vessels, proceed- 



of the shoulder or ledge beneath ing from the anterior ovarian 



tlie connective membrane of the group and coalescing with the 



anther, but does not bifurcate and column. In XTropedium, a genus 



extend to the two widely -separated which A. Brongniart (' Annal. 



viscid discs. des. So. Nat.,' 3rd series, Bot. torn. 



* From Irmisch's ('Beitr'age xiii. p. 114) considers closely allied 



zur Biologie der Orchideen,' 1853, to, and even perhaps a monstro- 



pp. 78 and 42) description of the sity of, Cypripedium, a third fer- 



development of the flower-bud of tile anther occupies this same 



Cypripedium, it would appear that position, 

 there is a tendency to tl;e forma- 



