Morphologie der Zellen, Gewebe and Organe. 245 



Nicht die Zellen spielen also nach Verf. bei der histologischen Differenzie- 

 rung der Tiere die maßgebende Rolle, sondern die vielkernigen Plasmodien; nicht 

 die Zellbildung, sondern die funktionelle Differenzierung der lebenden Masse, d. h. 

 der vielkernigen Plasmodien bildet das leitende Prinzip bei der Entwicklung der 

 Organismen. Die Zellen stellen nur eine, oft sehr vergängliche Form der leben- 

 digen Masse dar; eine tiefere Organisationsstufe sind die Granula. Oppel. 



742) Farmer, J. B. and Digfoy, L., On Dimensions of Chromosomes con- 

 sidered in relation to Phylogeny. In: Phil. Trans. Roy. Soc, Bd. B. 205 

 Nr. 313, S. 1—25, 2 pl., 1914. 



The objects of the authors have been to determine^l) how far the chromo- 

 somes can be taken as a safe indication of the kern-plasma relation; (2) how far 

 a comparison of their volumes may throw light on the nuclear Constitution of 

 such forms as Primula hybrids in which the chromosomes may be twice as nu- 

 merous as in the normal; and (3) whether certain of the generalizations of Meek 

 (cf. this Zentralblatt Bd. I, 1912, Nr. 841) are or are not well founded. They 

 find that in varieties of the fern Athyrium filix-focmina the chromosome number 

 affords no certain indication of the kern-plasma relation. In the hybrid Primula 

 keivensis [P. verticillata X P. floribunda) there are two forms, a sterile one 

 with 18, a fertile one with 36 chromosomes. The authors find that the total 

 amount of chromosome -substance in the nuclei of the two forms is the same; 

 the chromosomes of the form with 36 being half the size of those of the form 

 with 18. The doubled number is probably due to transverse fission of the chro- 

 mosomes. A number of animals and plants of various groups were examined, and 

 it was found that none have a constant chromosome width, that the width of 

 a chromosome is seldom uniform throughout its length, and that some species 

 have chromosomes of very varying widths. The conclusions of Meek with regard 

 to the relation between chromosome width and phylogenetic position are thus 

 not substantiated. Doncaster. 



743) Keed, T., The nature of the double spireme in Allium cepa. In: 

 . Annais of Botany, Bd. 28, Heft 2, S. 271—281, 1914. 



This study of somatic mitoses in the onion was chiefly made from root tips. 

 During the resting stage of the nucleus the bulk of the chromatin is found to 

 be stored in the nucleoli, the rest of the nucleus containing a fine reticulum. This 

 network is considered to be of the nature of a "thin fenestrated sphere". The 

 first indication of mitosis is the aggregation of the chromatin in band-like 

 masses on this framework. It slowly spreads and so forms the spireme ribbon, 

 which is believed to be at first continuous and is coiled in the nucleus. There 

 appears to be an actual transfer of substance from the nucleolus along tbe spi- 

 reme threads, the nucleoli being left as vacuolated, pale bodies, afterwards exten- 

 ded into the cytoplasm. Previously they often contain regularly shaped refrac- 

 tive bodies. The spireme in double almost from the first, owing to on early 

 split in the band. It is considered that this split first appears in the anaphase 

 of the preceding division. The spireme then Segments into probably 8 long, 

 twisted double bands. These afterwards break across the middle, giving rise to 

 the 16 somatic chromosomes, which are thus arranged in pairs on the equatorial 

 plate. While the chromosomes are passing to the poles a longitudinal split ap- 

 pears in them. This has usually been supposed to be a peculiarity of the hete- 

 rotypic anaphase. In telophase, lateral fusions occur between neighbouring chro- 

 mosomes. The nucleoli develope a new from knots in the chromatin. The game- 



