ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 573 



four nuclei an eight-nucleate sac is formed. At the time of fertilization 

 the egg-cell is large and pear-shaped with a large, round nucleus ; the 

 antipodals when stained show signs of disintegration and have a marked 

 tendency to enlarge ; the nucellus has been absorbed except in the 

 region of the micropyle ; the two polar nuclei fuse, and triple fusion has 

 also been observed ; the synergids entirely disappear. Subsequent to 

 fertilization the endosperm-nucleus undergoes mitotic division, giving 

 rise to free nuclei ; the latter are subsequently enclosed in cell-walls to 

 form multinucleate cells. The fertilized oospore gives rise to a two- 

 celled embryo, the basal cell of w^hich develops into a suspensor and the 

 terminal cell into the embryo proper. 



The mature emlnyo has a long, spindle-sliaped, succulent cotyledon 

 projecting into the endospei'm, where it absorbs food like a haustorium. 

 The number of rudimentary leaves varies according to the conditions 

 of growth, and the leaf -base is always closed. The primary root has 

 a well-developed root-cap. The entire development appears regular 

 when compared with the near relatives of this species. 



Embryogeny of Capsella.* — R. Soueges contributes a note upon the 

 first divisions of the egg-cell and the origin of the hypophysis in Capsella 

 Bursa-pastoris. The author finds that the basal cell of the pro-embryo 

 divides transversely to form two daughter-cells, the lower of which again 

 divides and gives rise to a large micropylar vesicle and a portion of the 

 suspensor filament ; the upper, or intermediate, cell of the pro-embryo 

 has meanwhile divided to form the greater part of the suspensor-filament 

 and the hypophysis cell. The apical cell divides vertically, and forms 

 the true embryonic cell. Thus it appears that the intermediate cell does 

 not originate in the apical cell, as is supposed by some authors, but arises 

 from the basal cell and the bicellular pro-embryo. 



General. 



Supposed Origin of Life.f — S. G. Paine has repeated the experi- 

 ments of Bastian, in order to test the claim of the latter to have 

 discovered the origin of living organisms from non-living materials. 

 Eighty-five tubes of colloidal silica were subjected to the treatment 

 recommended by Bastian, and the amorphous deposit which collected at 

 the bottom of the tubes was carefully examined. Forms somewhat 

 resembling organisms were found, but proved to be composed of silica. 

 These forms appear to be the so-called " fungus-germs " which were 

 regarded by Bastian as evidence of spontaneous generation of life. The 

 present work sho^^•s them to be " purely inorganic simulacra formed by a 

 slow deposition of silica from colloidal solution, and, in part, depositions 

 of silica upon dead fungal hyphse which had developed in the solutions 

 before these were filled into the tubes and sterilized." 



* Comptes Rendus, clxiii. (1916) pp. 158-60. 

 t Ann. Bot., xxx. (1916) pp. 383-88 (1 pi.). 



