52 Morphologie, Teratologie, Befruchtung, Cytologie. 



Chamberlain, C. J., Fertilization and embryogeny in 

 Dioon edule. (Bot. Gaz. L. p. 415—429. pls. 14 — 17. Dec. 1910.) 



In this Mexican cycad fertilization takes place during the latter 

 part of April or first part of May. The quantity of liquid exuded 

 from the pollen tube is not sufficient to cover the sperms, but it 

 reaches as far as the neck of an archegonium, where it plasmolizes 

 the neck cells, allowing a drop of protoplasm to escape from the 

 egg, and leaving a vacuole. This probably accounts for the entrance 

 of the sperm, since no chemotactic fluid has been found. Following 

 fertilization, nine or ten simultaneous free nuclear divisions occur, 

 giving rise to 512 or 1024 nuclei. At the seventh and eighth mitoses 

 evanescent cell walls are often formed, and at the ninth mitosis 

 walls are generally formed, but they disappear except from the basal 

 region, where they organize the suspensor and embryo. The sus- 

 pensor becomes much twisted, but when straightened out may mea- 

 sure 75 mm in length. A conspicuous coleorhiza is differentiated, 

 and is quite dffferent in appearance from the adjacent root-cap, 

 though both are morphologically one organ. In the ripe seed the 

 cotyledons constitute the chief mass of the embryo. 



M. A. Chrysler. 



Coulter, J. M. and C. J. Chamberlain. Morphology of Gym- 

 nosperms. (XI, 458 pp. 462 flg. Chicago, 1910.) 



This work is intended to replace vol. 1 of the authors' Morpho- 

 logy of Spermatophytes, published in 1901, but has been so largely 

 rewritten and extended as to become practically a new work. 

 Although each of the Orders of Gymnosperms is given about twice 

 the space formerly allotted, the most notable feature of the new 

 edition is the opening chapter on the Cycadofilicales, in which both 

 the vegetative and the reproductive structures receive adequate 

 treatment and are freely illustrated. In this section are included 

 some general remarks on the vascular anatomy of Pteropsida, which 

 makes possible a comparative discussion of the vascular structures 

 of the plants dealt with in this and other chapters. Chapter 2 on 

 Bennettitales and chapter 4 on Cordaitales contain matter transferred 

 from the chapter on "Fossil Gymnosperms" of the former edition, 

 as well as considerable new material. The chapter on Cycadales is 

 enriched by the researches of the Chicago laboratory on several 

 genera, especially Dioon and Zamia. Coniferales are dealt with 

 much more fully than in the first edition, and occupy two chapters, 

 on Pinaceae and Taxaceae respectively. The bibliography to these 

 chapters contains 181 titles, in contrast to the 49 of the former 

 edition, a fact which shows the extraordinary activity in this field 

 during the past ten years. The descriptive part of the book conclu- 

 des with an account of Gnetales. in which the recent contributions 

 of Pearson and of Land are given due prominence. The final 

 chapter "Evolutionary tendencies among gymnosperms", gives in 

 clear form the authors' views as to the phylogeny of the group, 

 and presents a comparative view of each of the organs of the 

 plant body. Throughout the book the spore rather than the spore 

 mother cell is recognized as the beginning of the gametophyte 

 generarion. A special chronological bibliography follows each chapter, 

 while a complete alphabetical bibliography appears at the end of 

 the volume. The numerous exceedingly satisfactory illustrations are 

 a highly commendable feature of the book. M. A. Chrysler. 



