82 Morphologie, Befruchtung, Teratologie, Cytologie. 



Blackman, V. H., The „Sexuality" of the Mucovineae. (The 

 New Phytologist, London. Vol. V. p. 215—219. 1906.) 



After summarizing Blakeslee's work on zygospore production 

 in the Mucovineae , the author points out that the development of 

 the zygospores of the heterothallic iorms can hardly be considered 

 an ordinary sexual process. The word sexual in its narrow sense 

 is applied only to those cases of reproduction in which there is a 

 differentiation of the fusing gametes. This is not the case in the 

 Mucorineae\ and the author considers them to be in an undifferen- 

 tiated condition as regards sex. The individuals here are characterised , 

 not by the formation of morphologically differentiated gametes, but 

 by a purely physiological differention, viz. that the gametes which 

 lead to the prodl^ction of zygospores are only formed when different 

 mycelia come in contact. 



The author traces the differentiation of sex as seen in Algae, 

 and concludes that the term sex as applied to organisms means 

 "that there is a binary differentiation of individuals, which are 

 distinguished primarily by the fact that they bear morphologically 

 and physiologically different types of gametes." The word syngamety 

 is suggested as a term to include all reproductive processes, which 

 exhibTt gametic union, without reference to the differentiation or 

 otherwise of the gametes. A. D. Cotton (Kew.) 



Mottier, D. M., The Embryology of some anomalous Dico- 

 tyledons. (Annais of Botany. XIX. p. 447—463. With twoplates. 1905.) 



The author summarises the work on embryo development in 

 certain Orders of the Dicotyledons and examines the embryology of 

 some plants of the Ranunculaceae and Papaveraceae. 



In Actea alba the youngest embryo observed consisted of a sort 

 suspensor and a club-shaped body. The cotyledonary primordium 

 arises as a thick concentric ridge from the broad end of the embryo , 

 the curved indentation on one side extending almost to the centre. 

 A cleft is then formed opposite the original sinus and the primordium 

 developes into two symmetrical cotyledons possessing a common 

 base. The inequality in the depths of the sinuses is somewhat 

 equalised in the mature seed. Sanguinaria canadensis resembles 

 Actea but the common base of the cotyledons undergoes intercalary 

 growth, causin^ the primary sinus to be deeper than the other. 

 Stylophortcni dipJiyUwin and Syndesmon thalictroides are typically 

 dicotyledonous, the sinuses showing a slight difference in depth in 

 certain individuals. In Delphinimn tvicorne the crescent shaped 

 primordium soon bifurcates but the difference in depth of the two 

 sinuses is more pronounced. A cotyledonary tube is present in the 

 embryo of the mature seed. Aqiälegia canadensis resembles Delphi- 

 nium but the anomaly is only very slight. 



The author concludes that the anomalous character represents 

 a derived and not a primitive condition. Consequently the anomalous 

 Dicotyledons do not show that one class of Angiosperms was derived 

 from the other. M. Wilson (Glasgow.) 



Stevens, W. C, Spore Formation in Botrychiuin virginianuni. 

 (Annais of Botany. XIX. p. 465-474. With 3 plates. 1905.) 



As soon as the leaves appear in the spring the spore mother 

 cells are found in the prophase of their first division; the nucleus 



