40 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 

 Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including- Cell Contents. 



Relation of Nucleus and Chromosomes.* — T. M. Mano has in- 

 vestigated the behaviour of the nucleus in the somatic cells of Solanum 

 tuberosum and Phaseolus vulgaris. This work was mainly undertaken 

 to test the views of Wager, which contradict those of Gregoire and 

 Wygaerts. Mano was unable to confirm the view of "Wager that the 

 nucleolus is morphologically transformed into chromosomes, though it 

 may furnish some substance for their development. The chromosomes 

 are derived directly from the chromatic network in the prophase ; and 

 in the anaphase the nucleolus arises independently of the chromatic net- 

 work in the form of drops which flow together to form a single 

 nucleolar mass. 



Achromatic Spindle of the Heterotypic Division.! — J. Berghs has 

 investigated the development of the pollen-mother-cell of Paris quadri- 

 folia. The nucleus is extraordinarily large, but the richness of the 

 nuclear material is not favourable for a study of the exact behaviour of 

 the chromosomes ; the development of the achromatic spindle can be 

 followed, however, with great clearness. In the development of the 

 spindle the author observed no distinction of kinoplasm and tropho- 

 plasm in the sense of Strasburger, but finds that the spindle is merely 

 formed by a rearrangement of the ordinary cytoplasmic reticulum. The 

 spindle is at first multipolar and becomes bipolar, not by a fusion of the 

 various minor cones to form two, but by the withdrawal of the fibres 

 constituting the secondary cones into the general spindle. 



UHeterotypic Division.^ — J- Berghs, in two short papers, describes 

 his investigations of this division in the pollen-mother-cells of 

 Oonvallariu, Drosera, Nartlmium, and Helleborus. In all these cases he 

 confirms the earlier view put forward by Gregoire and himself — that 

 the spireme is formed by the union side by side in synapsis of two 

 filaments ; that the later longitudinal splitting of the single thread is 

 merely the reappearance of these two threads. Portions of these threads 

 then become condensed to form the daughter-chromosomes, which thus 

 represent merely somatic chromosomes. The numerical reduction at 

 the prophase is thus merely apparent ; the true reduction in number 



* La Cellule, xxii. (1905) pp. 57-77 (4 pis.) 



+ Tom. cit., pp. 202-14 (2 pis.) 



J Tom. cit., pp. 43-53 (1 pi.) ; pp. 141-60 (2 pis.) 



