Dr Dickson on Diplostemonous Floivers, dc, 251 



Although we must avoid attaching undue weight to the 

 foregoing facts as to the Aurantiacese and Phihidelphacese — 

 the organogenic evidence being far from complete — yet it 

 may be allowed, I think, that such facts at least heighten 

 the presumption in favour of the justness of my views as to 

 the constitution of the androecium in Geranium, &c. If 

 my conjectures are well founded, it is possible that the 

 younger stamens in Tiplirasia and Deutzia may be found 

 to appear on the same circle with the older ones, just as in 

 Citrus and Pliiladelphus all the staminal lobes are on one 

 circle, or nearly so. 



Having stated my reasons for believing the diplostemony 

 in Geranium and the like, to be merely apparent, I would 

 now allude to certain objections which may be urged against 

 that view. 



It may be said that such diplostemony may occur in plants 

 whose leaves are neither lobed nor stipulate. In Malachium, 

 for example, the leaves are entire and ex-stipulate. Ee- 

 garding such an objection, I would observe that, in the case 

 of compound stamens, which I believe affords us the closest 

 analogy with this form of diplostemony, there is not only 

 no necessary coincidence between the lobed or compound 

 condition of the stamens and a similar condition of the 

 leaves in the same plant, but there is not even any neces- 



5 are superposed to the sepals, and 10, in 6 pairs, to the petals. The stamens 

 superposed to the sepals are the first deyeloped, and appear simultaneously. 

 In each of the pairs superposed to the petals, however, there is an older and a 

 younger stamen. From Payer's figure (Organogenie, pi. 154, fig. 25), it would 

 appear that the position of the older and younger stamen, in each pair, to 

 right and left, as regards each other, is uniform ; so that each of the primary 

 stamens superposed to the sepals has an older stamen on the one side and a 

 younger on the other. There is evidently here an alternate succession of 

 secondary staminal lobes, analogous, so far as it goes, to what has been 

 described by Payer in Malvaviscus, and by Payer and Baillon in Euphorhia. 

 Tlie androecium of Visnea cannot fail to recall that of Melhania decanthera, 

 described in a former note, and I have no doubt that the two cases are quite 

 analogous, only, the apices of the reduced staminal groups are represented by 

 staminodes in Melhania decanthera, the intervening unequal pairs of lobes being 

 alone fertile. 



Aristotelia, in the Tiliacese, is evidently also a reduced polyadelphous form, 

 being described as having 5 inner stamens superposed to the sepals, and 10 

 outer in 5 pairs superposed to the petals (Payer, Leqons mr les fam. nat., 

 p. 278.) 



