374 Literarisch-kritische Rundschau. 



alisation of tlie tigures sbown to Geige 1 by bis cytological Mend 

 tbat bave misled bim; and neitber tbe matbematician, wbo 

 accepted wbat was presented to bim, nor tbe cytologist, wbo was 

 probably content to accept tbe equation as it stood as a final 

 settlement of tbe matter by an expert wbose judgment it would 

 bave been presumptuous to doubt, can be beld blamewortby, but 

 ratber botb must be excused for tbeir good faitb : G e i g e P s in 

 tbe diagrams, tbe cytologist's in tbe equations. 



My own preparations are enougb to sbow tbe "lead" of 

 tbe axial cbromosomes ; but I am a very poor draftsman. I tbere- 

 fore reproduce copies of figures by Strasburger^) and 

 Vejdowsky ^). 



Sucb figures are scarce in literature for two reasons: 

 1. Cytologists naturally prefer sucb figures as are clear to decipber, 

 and demonstrative for tbeir purpose ; and bence, as far as possible 

 bave illustrated tbe process of discession from cells with but a 

 limited number of cbromosomes, wbicb consequently form a 

 peripberal crown on tbe spindle. (In passing I may note tbat 

 tbese sbow offen eacb cbromosome gliding along a Single tbread 

 passing continuously from pole to pole along tbe curved line of 

 force. In sucb cases tbere can be no question of " pull " or 

 " pusb " : tbere are neitber "Zug-" nor " Druckfasern " ^j. Tbe 

 frequent Separation of tbe centrosomes durin g tbe actual process 

 of mitosis demands neitber pull nor pusb, wben once we bave 



') Über den Teilungsvorgaug der Zellkerne etc. Arch. mikr. Anat., 

 XXI (1882). 



-) Neue Untersuchungen über Reifung und Befruchtung, 1907, Fig. 123. 



^) The Suggestion that some or all of the spindle-fibres exercise a 

 push rests on two grounds. The first is the recession of the centrosomes 

 during mitokinesis, which may be explained on other grounds; cytoplasmic 

 traction, and the mutual repulsion in virtue of their like electric and osmotic 

 charges, as we have seen : the second ground is the occasional Observation 

 that some of the achroraatin threads of the spindle may be irregularly bent, 

 or zigzag. This phenomenon is, I am convinced, due to the occasional failure 

 of the threads to foUow in their contraction the enormous contraction of 

 the more solid peripheral parts of the cytoplasm in the processes of fixing, 



dehydration, and Clearing We need badly a quantitative study of the 



shrinkage of histological specimens during the customary preparations. Even 

 so careful an investigator as C. F. M e e k in his measurements of cbromo- 

 somes and of spindles has this vital point iuadequately investigated. 

 (Quart. J. Micr. Sc, July 1913.) 



