Physiologie. — Palaeontologie. 407 



tion du depöt. La presence des bacteries ferrugineuses est acciden- 

 telle, non seulement dans les ocres en general, mais encore dans 

 une ocre de coloration et par consequent de composition determinee. 

 Les bacteries fixent le fer dans leur gaine et elles peuvent aussi for- 

 mer un enchevetrement qui retient mecaniquement le fer precipite 

 par voie chimique dans l'eau. Elles peuvent ainsi contribuer, non ä 

 la precipitation, mais ä la formation du depöt lä oü le fer precipite 

 et empecher celui-ci d'etre entralne par l'eau. Le meme phenomene 

 s'observe, au surplus, chez d'autres organismes que Ton rencontre 

 dans les eaux ferrugineuses, notamment les Algues vertes et les 

 Diatomees. Henri Micheels. 



Tichomiro"w , W. A., Le Glycogene des Champignons Asco- 

 mycetes dans ses rapports avec le trehalose. (Bull. Sc. 

 •pharm. XV. 1908. p. 189.) 



Plusieurs savants ont montre dejä l'importance du glycogene 

 chez les Champignons. L'auteur montre que le glj'^cogene forme 

 dans les jeunes tissus des Champignons {Terfesia, Choivomyces, Hyd- 

 notria, Tiiher etc.) engendrent du trehalose. F. Jadin. 



Arber, E. A. N. and J. Parkin. Studies on the Evolution of 

 the Angiosperms. The Relationship of the Angiosperms 

 to the Gnetales. (Ann. of Bot. Vol. XXIL p. 489—515, with 3 

 text-figures. 1908.) 



In this paper the strobilus theory, recently applied by thesame 

 authors to the problem of Angiospermous descent, is applied also 

 to the Gnetales in the hope that a reasonable hypothesis of the 

 relationship of the Angiosperms to the Gnetales may result. 



In a füll historical review, a summary is given of the attempts 

 which have been made to determine the place of the Gnetaceae in 

 ph3dogenetic schemes, and the various positions assigned to the 

 three genera in the chief natural Systems of Classification from the 

 time of Linnaeus onwards. 



The fructifications of the Gnetales are next considered in detail. 

 The amphisporangiate condition, present in the male fructification 

 of Welwitschia , is regarded as primitive, and as the key to the 

 'floral' morphology of the group. It is interpreted as a complete 

 pro-anthostrobilus possessing a perianth, microsporophylls, and, 

 at the apex of the strobilus, a megasporangium. From this primitive 

 strobilus, the female of the same plant, and both the male and 

 female strobili of Ephedra and Gnetum can be derived by reduction, 

 one set of organs, either male or female, being entirely suppressed. 

 These fuctifications are thus very reduced proanthostrobili, which 

 have originated from amphisporangiate strobili. 



A perianth is regarded as present in both the male and female 

 strobili of all three genera, of which diagrammatic relative plans 

 are given in the first text-figure. From the male strobilus of Wel- 

 witschia, where the perianth is less reduced, and consists of two 

 cycles of two members each, the Single perianth whorls of the 

 remaining strobili are easily derived. 



Attention is called to the dense aggregates in which the strobili 

 are collected, a feature which is regarded as indicative of a high 

 degree of evolution and a far from primitive State. 



The male organs have been greatly modified b)^ the reduction 

 and cohesion which has taken piace in the strobilus as a whole. 



