Febeuaby 22, 1907] 



SCIENCE 



283 



Cultures of the male gametopliyte in 

 saccharose solutions gave the following re- 

 sults: The exine is ruptured and its con- 

 tents completely freed. The body cell 

 gives rise to two elliptical male cells equal 

 in size and optical appearance. Later the 

 poUen tube appears and continues to 

 elongate for about twenty-four hours. 

 Fertilization is possible within ten hours 

 after pollination. Four days having 

 elapsed between the collecting of material 

 at Mesilla, N. M., and its fixation at the 

 University of Chicago, it was not possible 

 to observe stages in the progress of the 

 pollen tube to the egg. 



The fertilized egg gives rise to eight free 

 nuclei more or less unequal in size. The 

 number of cells which reach the suspensor 

 stage varies from two to five. Immediately 

 after the egg is fertilized the walls of the 

 jacket cells disappear and their contents 

 are mixed with the cytoplasm of the egg. 



The chromatin of the second male cell 

 and also that of the jacket cells seems to 

 be responsible for a mass of minute ephem- 

 eral cells. Possibly this mass of small 

 cells may be looked upon as at least sug- 

 gesting how the endosperm of angiosperms 

 may have originated. 



The functioning embryonal cells become 

 spherical. Two free nuclei are formed in 

 each embryonal cell and soon afterward 

 the suspensor appears. After the suspen- 

 sor reaches a considerable length one of 

 the free nuclei passes into it and down- 

 ward to the tip. Immediately above the 

 latter nucleus a ring of cleavage appears in 

 the cytoplasm, beginning at the suspensor 

 wall and gradually continuing inward 

 until the cytoplasm of the embryo is sepa- 

 rated from that of the suspensor. A wall 

 is then laid down and the separation is 

 complete. The suspensor nucleus passes 

 into the suspensor and takes a position near 

 the embryo, where it soon disintegrates. 



The walls of the embryo are laid down in 

 the usual manner on the cell plate. 



Under favorable conditions the develop- 

 ment of the embryo is continuous and the 

 young plant breaks out of the seed before 

 the strobilus is shed. From the time the 

 strobili can be recognized until the appear- 

 ance of the young plant about six months 

 elapses, being the shortest time yet re- 

 ported for any gymnosperm. 



Dioon and Ceratozamia: Dr. Chas. J. 



Chamberlain, University of Chicago. 



An account was given of a second trip 

 made to Mexico for the study of Dioon 

 and Ceratozamia, by the aid of a grant 

 from the Botanical Society of America. 



Fruiting specimens of Dioon spinulosum 

 were not found during the trip, but ma- 

 terial has been secured. There are fre- 

 quently more than two ovules on a sporo- 

 phyll, sometimes as many as five ; the seeds 

 are larger than those of any known cycad 

 except Cycas itself. The ovulate cones are 

 reported to be lateral. 



Ceratozamia was found in considerable 

 abundance. The motile sperms were 

 studied in the living condition and ma- 

 terial has been secured for a study of most 

 phases in the life history. The seeds are 

 small and are shed soon after fertilization, 

 so that there is a continuous development, 

 without any resting period, from fertiliza- 

 tion up to the leafy plant. 



A series of photographs were obtained, 

 of which lantern slides were shown. 



The Genus Pleurococcus Cviturally Con- 

 sidered: Dr. G. T. MooBE, Bureau of 

 Plant Industry. 



The Early Growth of MonostroTua and 

 Enteromorpha: Dr. Tract E. Hazen, 

 Barnard College. 



Our knowledge of early stages of growth 

 in the family Ulvacese is comparatively 

 meager. In the genus Monostroma, the 



