388 



ON THE VALUE OF CHARACTERS. 



may be adduced as another maximum instance. The usual absence of 

 a number of layers, which should exist, supposing the ordinary idea 

 to be correct, would lead us to adopt the idea suggested by Rosa, and 

 in this case Dr. Lindley is right in not attaching much importance to 

 mere perigynism Escholtzia is a strong proof in point, but it must be 

 seen whether the stamina really arise in this genus from the throat 

 of the calyx, in which case they will be hypogynous, or, whether they 

 terminate the glandular lining of the tube, in which case they will 

 be perigynous. The curious effect produced by auplication of the 

 stamina to the interior of the calyx is seen in Aquilarinea?, in which, 

 without any cohesion with this organ, they are united inter se into a 

 flat membrane. 



The freedom from cohesion in Amygdaleae, may arise from the abor- 

 tion of the other carpella. This will be indicated, if it be found 

 that in true Pomaceoe with fewer ovaria than ordinary, the cohesion 

 is less constant as well as less in degree. 



The proportion of the stipulate orders of Polypetalae, to the ex- 

 stipulate, is nearly as one to three, the total numbers of orders be- 

 ing 1 65, of which, 56 are stipulate. 



But while the number of monopetalous orders is 61, the number 

 of stipulate, is only 4, or rather more than one in fifteen. 



Stipulae are unknown among the naked seeded orders. 



The proportion in Monocotyledones in favour of ex-stipulation is 

 immense, the number of orders being 32, out of which only a por- 

 tion of a single order is stipulate. Hence these appendages may be 

 looked upon as a test of perfect evolution. Stipulae are frequeuly 

 characteristics of great groups, and in such cases great importance is 

 to be attached to their existence or presence, but they often occur as 

 isolated characters, affording admirable diagnostic marks. Occasion- 

 ally, their presence is not universal in a given order, and in such cases 

 their presence carries but little weight. Of the first, the great groups 

 of Malvacea and its allies, Rosaceae and its allies, CupuUiferae and its 

 allies, and the three groups included by most botanist in Leguminosae 

 may be adduced ; of the second, we have examples in Magnoliacese, 

 Cunoniaeeae, Rhamneae, Zygophylliae, Violarinese, and of the latter 

 in Euphorbiacese, Cistineae, and Myriceae. 



Among the stipulate polypetalous orders, 48 have alternate leaves, 

 5 opposite, two both opposite and alternate, with stipulary ciliae. 



