ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 207 



and has shown that in the antheridia the spermatozoids arise through a 

 repeated hipartition of the nucleus, i.e. on the same lines as the egg-cell 

 in the oogonium. Divisions occur in the antheridium which are sup- 

 pressed in the oogonium. 



The author first reviews in detail the course of division resulting in 

 the formation of the oogonium in Char a and Nitella, with special reler- 

 ence to the work of A. Braun, and more recently of Gotz. The sterile 

 cells (the Wendungszclle of A. Braun) are not to be considered, as 

 Gotz suggests, as representing a rudimentary archegonial-wall, but 

 their homology is to be sought in the cell-divisions which occur in the 

 young archegonium. Braun's term Wendangszelle implying an alte- 

 ration in the direction of growth is misleading. The meaning of the 

 sterile cells is probably nutritive. 



In the Bryophyta the author compares the early stages in develop- 

 ment of the antheridium of the Marchantiacese and the Jungermanniacese 

 with that of the typical Liverwort archegonium, and concludes that the 

 latter " corresponds to a half antheridium, or in other words, to such a 

 one in which one longitudinal half is become sterile." 



For the agreement in the plan of development of the male and female 

 organs in the Pteridophyta, the author refers to his previously published 

 * Organographie der Pflanzen.' 



Pteridophyta. 



Anatomy of the Gleicheniacese.* — L. A. Boodle has examined the 

 anatomy of the rhizome and petiole in various species of Gleichenia 

 and in Platyzoma microphyllum. In Gleichenia, with the exception of 

 G. pectinata, where it is solenostelic, the stem-structure is protostelic. 

 Platyzoma has a medullate stele with annular xylem and internal endo- 

 dermis. The xylem is mesarch with distinct groups of spiral protoxylem. 

 A single leaf-trace enters the petiole ; the xylem is usually in the form 

 of an arch with incurved ends. When the bundle is small there are one 

 median and two lateral protoxylem groups on the upper side, but in 

 larger bundles the protoxylems are more numerous. In several species 

 a nodal island is found in the xylem of the stele ; it contains phloem 

 and sclerenchyma, the latter surrounded by an endodermis. Platyzoma 

 has a collateial leaf-trace, but apparently a concentric petiolar bundle. 

 The roots are mostly tetrarch, but diarch in Platyzoma. 



Fibro vascular Chains of Filicinese.t — According to C. E. Bertraud 

 and F. Cornaille, the broadening of a fibrovascular chain is effected at 

 first by the extension of its elementary bundles, their number remaining 

 constant. "When the broadening is very great, the bundles split and 

 the chain loses its continuity. Under other circumstances, when a chain 

 widens, it either forms new groups of tracheas between those already 

 existing, or the old groups divide. A chain may become broader by the 

 addition of external divergents or by the addition of other chains. The 

 addition may take place in the chain, or at one of the extremities if the 

 chain is open. Examples are given ; and these results are discussed from 

 a mathematical point of view. 



* Ann. Bot., xv. (1901) pp. 703-47 (2 pis.). 



t Comptes Rendus, cxxxiii. (1901) pp. 1027-9, 1309-12. 



