ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 601 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including Cell-Contents. 



Autolysis of Mitosis.*— A. Oes has studied mitosis in Vicia Fdba, 

 Pisum sativum, Hdianthus annum, etc., with the following results. 

 Those cells where mitosis has just started, but where further develop- 

 ment has been prevented by the addition of chloroform, toluol, or any 

 similar substance, contain an enzyme which can dissolve chromatin. 

 This enzyme is most rapid in action during ineta-, ana-, and telophase, 

 slower during prophase, and very slow indeed in the resting nucleus. 

 In autolysis the spindle-threads can no longer be made out, while the 

 nuclear membrane and nucleolus of the resting nucleus remain un- 

 changed. Temperatures from 80-40° C. favour autolysis ; at 80-90° C. 

 it is completely destroyed. A dilute solution of substances like nitre 

 favour it, while the reverse effect is produced by copper-sulphate, etc. 

 The enzyme is readily destroyed by free acids, but is uninjured by 

 strong alkalis. Nuclein is probably destroyed by it, and the diminu- 

 tion of chromatic material during telophase is probably due to its 

 action. The experiments seem to oppose the view that hereditary 

 characters are transmitted through the chromatin. 



Cytology of Pollen-mother-cells of Agave attenuata.t — Er. de 

 Lary, who has studied the pollen-mother-cells of several of the Amaryl- 

 lidacesB, contributes a note upon Agave. Prior to synapsis the nucleus 

 is completely filled by a fine linin network, the filaments of which 

 bear small chromatin corpuscles ; but the author has been unable to 

 find any association in pairs of either the corpuscles or the filaments. 

 In the early synapsis stage there is no fusion in pairs of the chromatic 

 corpuscles, and a little later the chromatin granules appear in a single 

 row ; at no time is there any sign of longitudinal splitting or of fusion 

 of two filaments. It is probable that the chromosomes are formed 

 by concentration of the chromatin, similar to the chromosome-formation 

 of NympJma alba and Nuphar luteum. The author favours the view 

 held by Mottier in regard to other Monocotyledons, viz. the formation 

 of simple chromosomes by the transverse splitting of a double chromo- 

 some. Sometimes detached chromosomes form accessory nuclei during 

 the early stages, but they disappear later, either through fusion with the 

 main nucleus, or by absorption into the cytoplasm ; and the author 

 considers that this refutes the theory that supernumerary nuclei are 

 specially characteristic of hybrids. 



* Bot. Zeit., lxvi. (1908) pp. 89-120 (1 pi.), 

 t Comptes Rendus, cxlvi. (1908) pp. 833-fi. 



