240 HOMOLOGIES OF THE Chap. VIII 



all were observed excepting a^, which is the most 

 difficult one to trace, and apparently is oftenest absent. 

 In the Cypripedeae, again, all were traced except a^* 

 which, 1 feel pretty sure, was here really absent : in 

 this tribe the stamen (Ai) is represented by a con- 

 spicuous shield-like rudiment, and a^ and cio are 

 developed into two fertile anthers. In the Ophreae 

 and Neotteffi all were traced, with the important 

 exception of the vessels belonging to the three stamens 

 («!, a2, and a^) of the inner whorl. In Cepludantliera 

 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 (ai and a^) 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 



supplj'ing the fertile anther runs tion of a free filament in front of 



up the connective membrane be- the lobelhim, as in the case of 



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



does not bifurcate : the vessel to tliis will perhaps account for the 



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



of the shoulder or ledge beneath iug from tlie anterior ovarian 



the connective membrane of the group and coalescing with the 



autlier, but does not bifurcate and column. In Uropedium. a genus 



exteiuitothc two widely-separated which A. Brongninrt (* Annal. 



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



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



zur Biologic dcr Orchideen,' 18.53, to, and even perhaps a monstro- 



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



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



<3ypripedium, it would appear that position, 

 tbore is a tendency to the fcrma- 



