Morphologie der Zellen, Gewebe und Organe. 299 



is made in the selection index number for corn, and a formula is given, to be 

 applied to the same purpose in Beans. Gates (London). 



Hierzu: Nr. 811, 859, 861, 979, 1006, 1024. 



Morphologie der Zellen, Gewebe und Organe. 



839) Nagler,Kurt, Der gegenwärtige Stand unserer Erkenntnis von der Zelle 

 als Grundelement des Lebenden. In: Ann. d. Naturphil., Bd. 11, Heft 1, S. 99 

 bis 110, 1911. 



Verf. versucht auf Grund verschiedener Quellen eine Darstellung der Energiden- 

 lehre Max Hartmanns. Seine Ausführungen sollen zeigen, daß die Wissenschaft vom 

 Leben noch eine Fülle von Problemen in sich birgt, die man früher nie geahnt hat, 

 deren weiterer Ausbau aber verspricht, unserer Erkenntnis das zu leisten, wonach wir 

 auf Grund der Erscheinungen streben, nämlich die Begründung eines Monismus im 

 Naturgeschehen. W. May (Karlsruhe). 



840) Lawson, A. A. (Glasgow, University), Nuclear Osmosis as a Factor 

 in Mitosis. In: Trans. Roy. Soc. Edinburgh., Vol. XLVni, Pt. I, S. 137—161. 

 4 plates. 



From observations on the pollen-mother cells of several plants the author 

 puts forward a new interpretation of the physical basis of mitosis. He finds that 

 the nuclear membrane does not break down during spindle development, but 

 behaves as a permeable membrane would do under varying osmotic relations. The 

 chromatin increases in amount, and appears to cause a change in the osmotic 

 relations of the nuclear sap, followed by diffusion of the sap into the cytoplasm, 

 and so diminution in volume of the nucleus. The membrane thus closes in about 

 the chromosomes, uutil it closely envelops each, and instead of a simple osmotic 

 System there are now as many as there are chromosomes. The decrease in the 

 size of the nucleus causes tension in the surrounding reticular cytoplasm, drawing 

 it out into fibrils attached to the nuclear membrane and therefore subsequently 

 to the chromosomes. Thus arise the spindle threads; no evidence was obtained 

 that the threads grow into the nuclear area and attach themselves to chromo- 

 somes. There was also no evidence that the chromosomes are drawn to the poles 

 of the spindle by the threads; the fibrils may serve as guides, but take no active 

 part in the movement. The achromatic spindle is an expression of the state of 

 tension in the cytoplasm, caused by osmotic changes which result in the con- 

 traction of the nuclear membrane; it is not an active factor in mitosis. 



Doncaster (Cambridge). 



841) Meek, C. F. U. (Manchester, University), A metrical analysis of Chro- 

 mosome complexes, showing correlation of evolutionary develop- 

 ment and chromatin thread-width throughout the animal kingdom, 

 In: Philos. Trans. Roy. Soc, Ser. B, Vol. 203, No. 294, S. 1—74, (5 plates), 

 1912. 



The author of this important paper has studied and compared chromosomes 

 of several phyla of animals from a novel point of view, and his conclusions, if 

 confirmed, will largely alter our conceptions of the nature and behaviour of 

 chromosomes. His method has been to measure the width and length of the 

 chromosomes in the equatorial plate of somatic cells and of spermatogonial and 

 spermatocyte divisions of animals belonging to various phyla, and to compare 

 the sizes observed, not only in the different chromosomes of one species, but in 

 the chromosome complexes of species belonging to widely distinct groups. His 



