i9i 2] CURRENT LITERATURE 437 



The life history of Endophyllum Sempervivi is peculiarly interesting 

 because in that form the aecidiospores function as teleutospores. HoffmanK 

 finds that the binucleate basal cells arise from fusion of cells in the lower part 

 of the aecidium. The axis of fusion, however, may lie in any direction, and 

 there is no palisade-like arrangement of the fusion cells. The paired nuclei 

 of the aecidiospore fuse and the subsequent processes are like those in teleu- 

 tospores. The sporophyte phase is restricted to the aecidiospore mother cell 

 and the two cells (aecidiospore and intermediate cell) formed from it. 



In both of these forms the binucleate cells arise from the fusion of fertile 

 cells, whose contiguous walls are dissolved. In this respect the process differs 

 from the migration of nuclei through pores as described by Blackman in his 

 account of Phragmidium violaceum. 



In a short note Beauverie 23 reports further observations on the "cor- 

 puscules metachromatiques " which he finds in the mycelium of an unidenti- 

 fied rust of wheat and also in the host cells. The author now identifies these 

 bodies with the "excretion bodies" of Zach, and believes they remain in the 

 host cells after the hyphae themselves have been digested. — H. Hasselbring. 



Embryo sac of Gunnera. — Ever since the investigation of Gunncra (Halo- 

 ragidaceae) by Schnegg in 1902, the genus has been included with those inter- 

 esting angiosperms (as Peperomia) displaying an excessive number of nuclei 



mbry 



It was very desirable to study the 



situation more critically, and this has been done by Samuels^ for G. macro- 

 phylla. The sequence of events is as follows: The solitary hypodermal 

 archesporial cell (mother cell) develops directly into the embryo sac, no tetrad 

 in the ordinary sense being formed. At the first (heterotypic) division of its 

 nucleus the reduced number of chromosomes was repeatedly observed to be 12. 

 At the second division (four nuclei) two nuclei assume the micropylar polar posi- 

 tion, and the other two are against the wall of the sac in the equatorial plane, 

 and a little later move toward the antipodal pole. The polarity of the sac is 

 thus attained at the 4-nucleate state. At this time the inner integument fuses 

 to close the micropyle, and therefore the pollen tube was observed to pierce 

 the integuments to reach the sac. The numerous vacuoles that appear during 

 the second division fuse into a large central vacuole during the development 

 of polarity. At the third division (eight nuclei) the upper one of the two micro- 

 pylar nuclei divides to two nuclei side by side; and at the fourth division 

 (16 nuclei) each of these two nuclei divides to two nuclei vertically placed. 

 These four micropylar nuclei are the egg, the synergids, and the micropylar 



2 * Beauverie, J., La signification des corpuscules metachromatiques dans les 

 cellules de c6reales infestees par la rouille. Compt. Rend. Soc. Biol. 70: 461-463- 19"- 



24 Samuels, J. A., Etudes sur le d6veloppement du sac embryonnaire et sur la 

 foundation du Gunnera macrophylla Bl. Archiv fur Zellforsch. 8:53-i 2 °- P ls - J"5* 

 figs- 23. 191 2. 



