468 



SCIENCE. 



[N. a. Vol. XV. No. 377. 



that of the pigment layer. No indications of 

 muscle fibers or pigment are to bfe seen. Cer- 

 tain deeply staining coagula within the optic 

 cup give evidence of a vitreous body. Some 

 large, clearly marked cells, probably those of 

 the vitreous body, are found attached to the 

 surface of the retina. Evidences of a choroid 

 fissure are to be seen in the fact that the ven- 

 tral portion of the retina is thinner than the 

 dorsal in almost all specimens. In one case 

 the choroid fissure was found to persist. The 

 most striking feature, however, is the extreme 

 variation. The optic nerve enters the eye at 

 various angles. Variation occurs in all parts 

 of the eye, and is especially notable in the 

 measurements of the thickness of the retina 

 and the dimensions of the eye as a whole. 

 C. M. Child, 

 Secretary. 



BIOLOGICAL SOCIETY OF WASHINGTO^f. 



The 350th regular meeting was' held on 

 Saturday evening, February 22. 



C. H. Townsend spoke on 'The Present 

 Status of the Carp in American Waters,' say- 

 ing that in spite of much adverse comment 

 this fish was rapidly assuming an important 

 place in this country and that no less than 

 $400,000 worth was sold annually, largely in 

 New York. It was the source of the principal 

 fishery in the Illinois River where the bass 

 had increased in spite of statements that carp 

 destroyed the spawn and young of bass. The 

 speaker believed that when the proper methods 

 ■of raising and cooking carp were better appre- 

 ciated it would find much favor and be an 

 important article of food, especially among 

 those who could not afliord the prices for the 

 most desirable species. It would be impos- 

 sible to propagate the finer species of fish on 

 a sufficient scale to keep pace with our grow- 

 ing population and as the carp could be 

 readily raised it would supply the deficiency 

 caused by the lack of other fishes. 



C. P. Hartley presented a paper on 'The 

 Pollenation of Immature Flowers,' saying 

 that, in order to save labor, plant breeders 

 sometimes apply pollen to flowers at the time 

 they emasculate them. Because fair success 



has often resulted from this method it is now 

 quite universally taken for granted that pollen 

 placed on immature pistils will remain there 

 imtil the pistils are receptive and then fer- 

 tilize the flowers. Experiments with tobacco 

 prove that there are flowers that are killed and 

 caused to fall from the plants by being pol- 

 lenated before their pistils are mature; and 

 microscopic study of flowers so treated shows 

 that the pollen germinates on the stigmas 

 sending pollen tubes down the immature pis- 

 tils into the ovaries. This growth of pollen 

 tubes in the ovaries among ovules not suffi- 

 ciently mature to admit of fertilization causes 

 the flowers to fall. Tobacco flowers fall in 

 about thirty-six hours after being prematurely 

 pollenated. If pollenated when almost mature, 

 i. e., eighteen or twenty-four hours b.efore .the 

 flowers would have opened, many will set 

 fruit ; but if pollenated two, three or even four 

 days before maturity, the flowers invariably 

 fall, separating smoothly from the plant at 

 the base of the peduncles. 



Datura flowers are also killed iy premature 

 pollenation, though unlike tobacco flowers they 

 do not fall but wither away and fail to develop 

 seeds. Doubtless other kinds of flowers will 

 be found to be injured by premature pollena- 

 tion. The growth of the pistils of cotton blos- 

 soms is checked by premature pollenation and 

 flowers pollenated one day before maturity do 

 not set so many nor produce as good fruits 

 as those pollenated at maturity. Tomato blos- 

 soms fail to set fruit when pollenated six days 

 before maturity, the failure being due to loss 

 of vitality in the pollen. If the flowers on 

 becoming mature be again pollenated they set 

 fruits. Orange blossoms pollenated nine days 

 before maturity are not injured but continue 

 their growth and mature good fruits. This is 

 true of seedy as well as of navel oranges and 

 the fact that flowers of the navel oranges so 

 treated result in fruits containing good seeds,, 

 proves that the pollen so early placed on the 

 stigmas successfully fertilizes the flowers. 



The experiinents show that certain kinds of 

 flowers are killed by being pollenated too 

 young; other kinds fail to set fruit because 

 the pollen placed on the young stigma loses its 

 vitality before the pistil becomes receptive. 



