1843 '862] HOMOLOGIES 275 



strongly R. Brown, for I have succeeded (perhaps he did, but Letter 603 

 he does not say so) in tracing the vessels belonging to each 

 organ in front of each other to the same bundle in the 

 ovarium : thus the vessels going to the lower sepal, to the 

 side of the labellum, and to one stigma (when there are two) 

 all distinctly branch from one ovarian bundle. So in other 

 cases, but I have not completely traced (only seen) that going 

 to the rostellum. But here comes my only point of novelty : 

 in all orchids as yet looked at (even one with so simple a 

 labellum as Gymnadenia and Malaxis] the vessels on the two 

 sides of the labellum are derived from the bundle which goes 

 to the lower sepal, as in the diagram. This leads me to 

 conclude that the labellum is always a compound organ. 

 Now I want to know whether it is conceivable that the 

 vessels coming from one main bundle should penetrate an 

 organ (the labellum) which receives its vessels from another 

 main bundle ? Does it not imply that all that part of the 

 labellum which is supplied by vessels coming from a lateral 

 bundle must be part of a primordially distinct organ, however 

 closely the two may have become united ? It is curious 

 in Gymnadenia to trace the middle anterior bundle in the 

 ovarium : when it comes to the orifice of the nectary it turns 

 and runs right down it, then comes up the opposite side and 

 runs to the apex of the labellum, whence each side of the 

 nectary is supplied by vessels from the bundles, coming from 

 the lower sepals. Hence even the thin nectary is essentially, 

 I infer, tripartite ; hence its tendency to bifurcation at its top. 

 This view of the labellum always consisting of three organs 

 (I believe four when thick, as in Mormodes^ at base) seems to 

 me to explain its great size and tripartite form, compared 

 with the other petals. Certainly, if I may trust the vessels, 

 the simple labellum of Gymnadenia consists of three organs 

 soldered together. Forgive me for writing at such length ; 

 a very brief answer will suffice. I am desperately interested 

 in the subject : the destiny of the whole human race is as 

 nothing to the course of vessels of orchids. . . . 



What plant has the most complex single stigma and 

 pistil? The most complex I, in my ignorance, can think 

 of is in Iris. I want to know whether anything beats in 

 modification the rostellum of Catasetum. To-morrow I mean 

 to be at Catasetum. Hurrah! What species is it? It is 



