266 Cross — Eupatorium ageratoides and coelestinum. 



lum, or from one plant to another. The results throughout 

 show that fertilization under these conditions did occur. 

 If the pollen be carried by the wind, it will as in the case of 

 insect agency, be deposited upon the fully matured pistils 

 — but the results recorded in the following tables do not 

 show that fertilization by means of wind did occur ; for 

 though the pollen was abundantly distributed over the 

 entire inflorescence and the inside of the covering of the 

 protected heads, the seeds could not be made to germinate 

 under the same conditions as those grown upon unprotected 

 plants. Moreover, the colors of the flowers and the abund- 

 ance of nectar secreted, would indicate entomophilous 

 fertilization, while the anthers are shorter than the corolla, 

 united in a tube and dehisce introrsely — conditions unfavor- 

 able to wind pollination. From the time of pollination to 

 the time when the fruits are ripe, a period of eight to ten 

 days elapses. Previous to pollination the ovarian wall is 

 clear, pale, and delicate in appearance. In surface view it 

 shows very long cells, each containing a row of transparent, 

 circular areas at irregular intervals — Fig. 9. Cross-section 

 — Fig. 10 — shows five layers, each of which is composed of 

 cells of uniform size, except the innermost — Fig. 10 i — 

 which shows smaller cells. Soon after pollination the 

 fourth layer from the outer surface has pigment deposited 

 in it, which gives a most delicate ecru tint to the wall. As 

 the fruit matures the pigment is gradually deposited in the 

 fourth layer between the circular areas, whose perimeters 

 are much thickened, forming chimney-like openings (Fig. 

 10 k). The wall passes through every shade of brown, 

 until at maturity it is very dark brown. During the period 

 from pollination to maturity, no change occurs in the 

 circular areas. H. M. Ward * suggested in a recent 

 publication that the pigmenting of the maturing fruit 

 is a provision intended to act as a color screen against 

 the blue violet rays, "as these rays would otherwise 



* ' ' Further Experiments on the Action of Light on Bacillus A7ithracis" 

 by H. Marshall Ward. 



