Cytologie und Befruchtung. 243 



zu unterscheiden sind. Der eine Fall wird durch die terni- 

 foliaten Gardenien repräsentirt, bei welchen keine Beziehung 

 zwischen anisophyller Ausbildung und Beleuchtung mehr zu er- 

 kennen ist. Als wahrscheinliche Ursache derselben ist hier eine 

 extrem ausgebildete Form der Exotrophie anzunehmen. In dem 

 häufigen Falle hingegen, in welchem die Anisophyllie einen 

 sichtlichen Beleuchtungsvortheil schafft, ohne dass aber das 

 Licht die Anisophyllie direkt hervorzurufen vermag, ist zu ver- 

 muthen, dass die Anisophyllie ursprünglich, durch Lichtwirkung 

 bedingt, erblich festgehalten wurde. k. Linsbauer (Wien). 



COKER, W. C v Ön the Gametophytes and Embryo of Taxo- 

 dlum. (Botanical Gazette. Vol. XXXVI. 1903. p. 1—27, 

 114—140. Plates 1 — 11.) 



The staminate cones begin to develop in autumn and pass 

 the winter in the pollen mother-cell stage. The reducing divi- 

 sion in the pollen mother-cells takes place in the spring, the 

 number of chromosomes being, probably, twelve. No sterile 

 prothailial cells are formed in the microspore. At maturity, 

 there are four nuclei in the pollen tube, viz., the nucleus of the 

 stalk cell, the nuclei of the two sperm cells and the tube nucleus. 

 The sperm cells are surrounded by a Haut Schicht and con- 

 tain a dense layer of starch about the nucleus and a peripheral 

 layer containing globules of plastic material. 



The ovulate cones also appear in autumn and grow, as 

 weather permits, throughout the winter. At pollination, a Single 

 megaspore mother-cell is distinguishable. The archegonia are 

 arranged as in the Cupresseae. The number of neck cells varies 

 from two to sixteen or more. The central cell contains two 

 kinoplasmic areas, one above and the other below a central 

 vacuole. A ventral canal nucleus is cut off but is not separated 

 from the cytoplasm of the egg by any wall. After fertilization 

 it divides amitotically. The egg nucleus contains a Iarge 

 amount of granulär material but a chromatin reticulum is alvvays 

 present. 



Fertilization takes place about the middle of June. Two 

 or more sperm cells may enter an archegonium but, usually, 

 one pollen tube fertilizes two eggs. The entire sperm cell 

 enters the egg and enfolds the egg nucleus. After fusion, the 

 starch and cytoplasm of the sperm cell pass to the base of the 

 archegonium with the fusion nucleus and take part in the for- 

 mation of the embryo. 



Eight free nuclei are formed and become arranged in two 

 tiers before cell walls are formed. The suspensors, as they 

 «longate, may or may not separate, and thus one or several 

 embryos may be formed from one archegonium. 



The family, Taxodieae, is regarded as artificial. Taxodium 

 should be removed to the Cupresseae. 



Charles J. Chamberlain (Chicago). 



• 16* 



