BIOLOGY. 289 



vanced. The plan on which the male and female organs are 

 formed is evidently a common one ; and the only reason why 

 some flower-heads have a pistil in the centre, and others are 

 wholly staminate, is, that there is greater axial vigor when the 

 female flower is formed. Whenever the common peduncle (below 

 the scarlet involucre) is weak, a pistil never appears in that head 

 of flowers. A few which seem strong neither have them ; but the 

 great majority of the strong peduncles are those which bear the 

 female blossoms. Another interesting fact is that the number of 

 male flowers is less in those heads which also bear a female than 

 -in those which are wholly staminate. This seems to add to the 

 point I made in my paper on Ambrosia, that after the flowers have 

 been partially formed in embryo, and before the sex has been 

 finally determined, the female flower, being primordially the 

 stronger, has the power of absorbing the males, or their partially 

 formed elements, into its system. It is certainly remarkable that 

 in both these instances the number of male flowers should decrease 

 in proportion to the existence or vigor of the central female one. 

 The male and female flowers of Euphorbia fulgens are formed 

 much alike ; the female occupies the centre, and seems really but 

 a prolongation of the main stem, on the top of which is an articu- 

 lation from which the ovarium springs. The capsula readily falls 

 from this articulation when mature. From the base of the female 

 central peduncle spring weaker peduncles, colorless, appearing, 

 indeed, almost like filaments, articulated at about the same height 

 as the female, only above the point bearing a short filament and 

 anther, the caduceous part before referred to. No one can fail 

 to see the correspondence of plan in these different parts, and I 

 think that nothing but the favorable position in the direct line of 

 axial vigor made the central flower a female one. Cases occa- 

 sionally occur in which a tolerably strong head of wholly male 

 flowers will develop the central axis into a pedicel almost as long 

 and vigorous as those which bear female flowers. But the flow 

 of vital force if I am correct in using this term not being 

 quite sufficient, the final goal of natural perfection in the female 

 form was not reached. These cases do not occur often, but are 

 well worth looking for, as they show so clearly the dividing line 

 between the forces which govern the male or female sex. -46- 

 stract of a paper read by Thomas Meehan before Phil. Academy of 

 Natural Sciences. 



MOVEMENTS OF CHLOROPHYLL. 



A series of observations have been made by Prillieux, Rose, and 

 Brongniart, on the apparently spontaneous movements within 

 the leaves of plants of the grains of chlorophyll which constitute 

 the green coloring matter. These grains had been noticed by 

 previous observers to congregate under the direct action of light. 

 M. Prillieux performed his experiments on a species of moss. 

 When the moss had been kept in the dark for some days, the cells 

 presented the appearance of a green net-work, between the 

 meshes of which was a clear, transparent ground. Ail the grains 



