188 ALTERATION OF POSITION. 



ceptible. It cannot at present be stated wliat precise 

 circumstances induce the one mass to form mother-cells 

 and pollen -grains, and the other to develop an embryo 

 sac and germinal vesicles. Position and external cir- 

 cumstances may have some indirect effect, and it may, 

 perhaps, be significant that in all the instances of 

 polliniferous ovules, the ovular structures have been 

 exposed on an open carpel or otherwise, in place of 

 being confined within the cavity of a closed ovary, as 

 under ordinary circumstances. Even among Conifers 

 the ovuligerous scales are so closely packed that there 

 is little or no exposure of the ovules. But, apart from 

 all speculative notions as to the relation between the 

 structure and functions of the anther and of the ovule 

 respectively, and of the possibihty or the reverse of 

 parthenogenesis, it will clearly be necessary in any 

 future alleged occurrence of the latter phenomenon to 

 ascertain whether any or all of the apparent ovules are, 

 or are not, anthers in disguise. 



Homomorphic flowers of " CompositaB." In a large section 

 of the Gom])osit(e there is, as is well known, a distinction 

 between the florets of the "disc" and those of the 

 " ray," the latter being ligulate, the former tubular. 



In what are erroneously called double flowers in this 

 order, e. g. in the Chrysanthemum, Dahlia, &c. &c., the 

 florets are all ligulate. This change is sometimes 

 classed with peloria, but there is no abnormal regu- 

 larity in these cases. On the other hand, were the 

 ligulate florets to be all replaced by tubular ones, the 

 term peloria would be more strictly applicable. It will 

 be remembered that in the sub-order LiguUflorce.^ the 

 florets are naturally all ligulate, so that the change 

 above mentioned is not in itself a very grave one. 



Heterotaxy affecting the inflorescence. Under the head of 

 Prolification, lloterogamy, &c., various deviations from 

 the normal inflorescence are alluded to. In this place, 

 therefore, it is only necessary to mention certain rare 



