908 RECORD OF CURRENT RESEARCHES RELATING TO 



between the roUed-in margin and the median line of the entire fertile 

 scale. The position of the ovule on the back of the bract in the 

 bud shows that it cannot possibly be an axillary shoot to this bract. 

 Another corroboration of the ovular theory and gymnospermy of 

 Conifers is that, as far as has at present been observed, the ovules, in 

 retrograde metamorphosis, never develop into shoots, but begin to 

 disappear as soon as the metamorphosis commences. 



The general result of Celakovsky's observation is — in opposition 

 to the earlier view of Strasburger — to confirm the prevalent theory 

 that the ovule of Conifers is truly gymnospermous. 



Reproductive Organs of Cycadese.* — In sequel to his observa- 

 tions published in 1877, M, Warming has re-examined the subject 

 with fresh material. The principal results before arrived at are 

 fully confirmed ; but he now considers that both Strasburger and him- 

 self were in error in the supposed observation of a canal-cell to the 

 " archegonium " ; what he previously described as such ho now 

 believes to be a large nucleus of the central cell which descends 

 towards its lower extremity. M. Warming also confirms the re- 

 markable observation that in Ceratozamia the embryo is never formed 

 in the seed until after having been sown in the soil. The embryo 

 has only a single cotyledon, which is unilateral, and embraces the 

 summit of the stem ; the radicle and the tigellum are very short in 

 proportion to that of the pro-embryo ; their structure appears to be 

 identical with that of Conifer£e. 



True Mode of Fecundation of Zostera marina.f — According to 

 M. A. Clavaud, it is not correct, as generally supposed, that the 

 anthers fertilize the pistils of flowers enclosed in the same spathe, 

 these organs not being nearly mature at the same time. There 

 is dichogamy and proterogynous dichogamy. Neither is the asser- 

 tion correct that the extremity of the pollen-cell penetrates into 

 the ovary through a stylar canal open at the summit of the stig- 

 matic branches. This apical opening does not exist, and the ex- 

 tremity of the iiollen-cell is inert. The pollen-tube does not grow 

 from the terminal elongation of the pollen-grain ; it is always a 

 lateral swelling situated at a certain distance from this extremity, 

 which, when applied to any point of the stigmatic surface, penetrates 

 by means of a notable " gelification " of the walls, which j)roduces 

 later the destruction of the stigmata. 



Arrangement and Growth of Cells.:}: — Professor Sachs has been 

 pursuing his investigation of these difficult subjects in the Botanical 

 Institute at Wiirzburg, and contributes a further instalment of 

 results. 



The chief point which he desires to bring forward with respect to 

 the growth of cells is that the normal direction for the formation of 

 a new wall is always at right angles to that from which it starts, and 



* 'Bull. Acad. Roy. Copenhague,' 1879, p. 73; French resume, p. 9. 

 t ' Acta Sue. Linn. Norinandie,' ii. p. 109 ; ' Bull. Soc. Belg. Micr.,' v. (1879) 

 p. 197 ; see ' Bot. Zeit ,' xxxvii. (1879) p. 535. 

 X 'Arb. Bot. Inst. Wiirzburg,' ii. (1879) p. 185. 



