CuAP. VIII. FLOWJfRS OF ORCHIDS. 235 



the whorls, E. Brown offers no sufficient evidence, but 

 believes that they are combined with the labellum, 

 whenever that organ presents crests or ridges. In 

 these views Brown is followed by Lindley.* 



Brown traced the spiral vessels in the ilower by 

 making transverse sections, f and only occasionally, as 

 far as it appears, by longitudinal sections. As spiral 

 vessels are developed at a very early period of growth, 

 and this circumstance always gives much value to a 

 part in making out homologies ; and as they are ap- 

 parently of high functional importance, though their 

 function is not well known, it appeared to me, guided 

 also by the advice of Dr. Hooker, to be worth while to 

 trace upwards all the spiral vessels from the; six groups 

 surrounding the ovarium. Of the six ovarian groups 

 of vessels, I will call (though not correctly) that under 

 the labellum the anterior group ; that under the 

 upper sepal the posterior group ; and the two groups 

 on the two sides of the ovarium the antero-lateral and 

 posterolateral groups. 



The result of my dissections is given in the following 

 diagram (fig. 36). The fifteen little circles represent 



* Professor Asa Gray has de- the union of one petal with two 



Bcrilied in the ' American Journal petaloid stamens. 



ofScience.' July ]86t),amonstroua t ' Linn. Transact.' vol. xvi. p. 



Qoviei ol Cypripedium candidum, 696-701. Link in his 'Bemer- 



and remarks on it, " here w e have kungen uber der Ban der Orchi- 



(aiid perhaps the first direct) deen'('BotanischeZeitung,'1849, 



demonstration that the oichideoua p. 745) seems to have also trusted 



type of flower has two ^tanlinal to transverse sections. Had he 



verticils, as Brown always in- traced the vessels upwards I cau- 



siott'd." Dr. Criiger alto advances not believe that he would have 



evidence ( ' Journ. Linn. Soc. disputed Brown's view of the 



Bot.' vol. viii. 1864, p. 132) in nature of the two anthers in 



favour of the presence of five Cypripedium. Brongniart in his 



whorls of organs ; but he denies admirable paper (' Annales dea 



that the homologies of the parts Sciences Nat.' torn. xxiv. 1831 ) 



can be deduced from the course of incidentally shows the course of 



the vessels, and lie does not admit some of the spiral vessels, 

 that the labellum is formed by 



