364 SUMMARY OF CURRENT RESEARCHES RELATING TO 



position, and divide, by transverse septa, into three superposed cells. 

 Of the four or five rows of cells thus formed, the uppermost daughter- 

 cell of one only developes, and becomes the embryo-sac ; all the rest 

 are resorbed, including the two belonging to the same row. Since 

 each of the originally free lobes from the central papilla forms an 

 embryo-sac, and the number of these lobes corresponds to that of the 

 carpels, the number of embryo-sacs in the ovary also corresponds to 

 that of the carpels. Round the embryo-sac is formed, partly out of 

 the previous epidermal cells of the central papilla, a sheath of amy- 

 laceous cells, which is prolonged upwards into a similar row, while 

 in the lower part of the ovary is developed a sheath of collen- 

 cbymatous tissue open above. The embryo-sacs elongate to an extra- 

 ordinary extent both upwards and downwards, following upwards the 

 row of amylaceous cells till they reach the base of the style, and there 

 somewhat expand ; while they extend dow^nwards to the base of the 

 collenchymatous sheath. Their nucleus now divides ; one of the 

 daughter-nuclei moves into the upper expanded portion of the sac 

 and again divides. 



The first wall in the fertilized germinal cell is longitudinal, 

 followed in each half by several transverse septa. The lower cells 

 of this suspensor divide further, while the upper ones grow to an 

 extraordinary length, and force the lower apex of the embryo between 

 the first endosperm-cells, which have at the same time been formed 

 in the lower part of the embryo-sac ; the embryo being thus finally 

 attached to the end of the double thread which constitutes the sus- 

 pensor, and which is rolled up between the embryo and the endo- 

 sperm. The endosperm cells now increase rapidly in number in its 

 lower and peripheral parts, thus crushing the suspensor, which finally 

 entirely disappears. The radicular end of the embryo then penetrates 

 into the endosperm and consumes it ; and the embryo becomes com- 

 pletely enclosed in the collenchymatous sheath ; rising up into it, 

 partly in consequence of the pressure of the lower part of the endo- 

 sperm. 



The central papilla formed in the centre of the ovarian cavity was 

 regarded by Griffith as a placenta with rudimentary ovules ; by Hof- 

 meister as an orthotropous nucleus without integuments, in which 

 several embryo-sacs are formed, and the chalaza of which is repre- 

 sented by the collenchymatous sheath. Treub supports the former 

 view, and considers the axial portion of the papilla to be of the 

 nature of a placenta, its three or four lobes being rudimentary 

 ovules ; a view confirmed by the somewhat similar structure presented 

 by the Santalacese. Griffith thought that the single embryo was the 

 result of the coalescence of several ; Treub is unable to confirm this ; 

 but, on the other hand, found frequent evidence of the abortion of 

 embryos, one only of which reaches maturity. 



Structure and Mode of Formation of Spermatozoids.* — 

 E. Zacharias has investigated the behaviour with different reagents of 

 the various constituents of spermatozoids, chiefly those of Nitella 



* Bot. Ztg., xxxix. (IS81) pp. 827-38, 846-52. 



