Literarisch-kritische Rundschau. 377 



(5) Where the achromatic spindle contains only as many 

 tbreads as there are chromosomes it is irnpossible to 

 invoke "pull" or "push", and the motion of the chromo- 

 somes must be diie to centred force acting along the 

 lines of the spindle tibres. 



(6) The zigzag irregularities sometimes found in the spindle 

 fibres, and often ascribed to "push" along them, is probably 

 an artefact due to irregularity of contraction during 

 histological preparation. 



(7) G ei gel in his discussion on fertilisation has omitted to 

 take into account the differences between physiological 

 and purely physical response, as illustrated by the facts 

 of the "threshold" minimum Stimulus, and by the 

 F e c h n e r - W e b e r law. 



(8) In the interests of biology it is most desirable that 

 competent physicists should study and discuss biological 

 theories and hypotheses. 



Description of Figures. 



Fig. 1. Distribution of equipotential zones (dotted) in an axial section of 

 a homogeneous iield about two equal centres of opposite sign; the 

 continuous lines are the lines of force (after J. J. Thomson). 



Fig. 2. Distribution of equipotential zones in an axial section of a homo- 

 geneous field about two centres of like sign. 



Fig. 3 and 4. Anaphases in endosperm after Strasburger (Arch. m. A., 

 t. 23) ; Fig. 3 G a 1 a n t h u s nivalis (t. 23, Figs. 52, 53) ; Fig. 4 

 Lilium croceum (t. 23, Figs. 41, 42). 



Fig. 5. Anaphase in first maturation spindle of Rhynchelnis pallida, 

 after Vejdowsk^. 



Fig. 6 and 7. Reproductions of Geigel's Fig. 2, 3; perspective views of 

 a two simple crowns of daughter chromosomes in anaphase, those 

 on the far side beiug indicated by the lighter shading. 



