380 ON CHORISIS. 



dian Institute in Feby. I860, and published in Vol. V. of the '' Jour- 

 nal, p. 382, to which I now refer. I accept the quaternary symmetry 

 in Brassicaceae, but consider the two lower stamens as part of an ex- 

 terior circle of which two glands frequently present represent the other 

 two members. I see no pretence for regarding the two pairs of stamens 

 as each representing one divided organ, and I explained in consistency 

 with my own view all the facts produced. Dr. Gray's second exam- 

 ple is found in the androecium of Fumariaceae. This consists appar- 

 ently of six stamens in two groups of three each, and Dr. &ray regards 

 them as really two organs, each divided into three by collateral chorisis. 

 It is to be observed that the two lateral stamens of each group hare 

 one anther each, while the central one has two. This suggested the 

 theory of DeCandolle, supported by Lindley, that there are really two 

 pairs of stamens, but those which were in the direction of the lateral 

 pressure are split into halves, one half of each being pushed close to 

 the stamens of the other pair, so as to place the perfect stamen of each 

 end between two half stamens divided from the other pair. The Bras- 

 sicaceous monstrosity recorded in which an outer stamen is split so as to 

 resemble two each with a single anther, greatly supports this explanation 

 which is favored also by the separated anthers, one on each side the 

 column from the single stamen of many Orchidaceae and the instances 

 of widely separated anthers with a partially divided filament. On this 

 supposition there may be said to be a chorisis, but it is one of the most 

 intelligible kind as there is no creation of an additional anther or of any- 

 thing more than is present in the undivided stamen. It must be re- 

 membered that as chorisis is assumed to be a division from above, the 

 three stamens in Dicentra being ofien quite distinct below and only 

 coherent in the middle is very unfavorable to, I should almost say ab- 

 solutely inconsistent with Dr. Gray's theory, and whilst this example 

 is before us it is vain to appeal to the more complete union in other 

 Fumariaceae, as it is an obvious case of coherence. 



Dr. Gray's third example is one of those cases which appears to me 

 to justify the admission of the principle of chorisis as occasionally giving 

 us a satisfactory explanation of structures which without it seem in- 

 comprehensible. He refers to the three groups of stamens each com- 

 pletely united at their base in Elodea : justly observing that though 

 the two outer circles in this flower are pentamerous, the inner ones 

 three in number, the carpels, the three groups of stamens, and the 

 three glands are trimerous so that each group of three connected sta- 



