Fortpflanzuno:. 447 



Capillitium formation is thus a process of intraprotoplasmic secretion and 

 luust be considered an adaptive morphogenetic process. Tlie threads are com- 

 pared to tlie endoskeleton of Radiolaria. Three facts regarding the formation 

 of the threads are established: 



1. The process is initiated by the liberation of water and the formation of 

 vacuoles in the cytoplasm. 



2. The vacuolar sap contains materials in Solution which are later used up 

 to form the capillitial wall and spirals. 



3. The spirals are laid down as organized granulär material, in definite 

 form on the outside of the vacuolar membrane. Gates. 



1187)Mottier,D.M., Mitosis in the pollen mother-cells of Acer negimdo 

 L. and Stuphylea (rifolia L. In: Annais of Botany, Bd. 28, Heft 1,S. 115 bis 

 133, 1914. 



Gives an account of the meiotic divisions in these two plants. The main 

 points may be mentioned. There is found to be no evidence for prochromosomes in 

 the resting nucleus. Synapsis is due to a real contraction of the nuclear Contents 

 and subsequent arrangement of the chromatin in a single spireme. From this de- 

 velopes the thick hollow spireme, which in Acer appears never to undergo a 

 split. The second contraction follows, which is concerned with the segmentation 

 of the spireme into chromosomes. The latter are at first arranged end to end, 

 but afterwards loops and rings are formed. The nucleolus does not form several 

 of the chiomosomes as suggested by Darling. In interkinesis the nuclei were ob- 

 served to pass more or less completely into the resting condition. 



The haploid number of chromosomes is about 12 in Acer negiindo, 36 in 

 Acer rubrum and 36 in Staphylea trifolia. Gates. 



1188) Meek, C. F. T., The ratio between spindle-lengths in the Sper- 

 matocyte metaphases of Helix pomatia. In: Proc. Royal Soc, Bd. B 87, 

 Nr. 504, S. 192—197, 1 PL, 1914. 



As the author had previously found in Forficula, the ratio between the 

 spindle lengths in metaphase of the primary and secondary spermatocytes of 

 Helix pomatia is approximately 1.26 : 1, the same, namely, as the ratio between 

 the radii of two spheres one of which has twice the volume of the other. The 

 author quotes a letter from von Winiwarter, saying that he finds the same ratio 

 in spermatocytes of Man. On the other hand, a comparison of the three species 

 shows that the spindle length cannot be correlated with the volume of chroma- 

 tin in the respective nuclei. Doncaster. 



1189) Loel), J., Artificial Parthenogenesis and Fertilization. Chicago 

 University Press (Cambridge Univ. Press, England) 1914. 8 vo. 312 S. Trans- 

 lation by W. 0. R. King, revised and enlarged by the author. 



This is a revised translation of the author's book (1909) „Die chemische 

 Entwicklungserregung des tierischen Eies". It gives a very complete account of 

 our present knowledge of the subject, with details of methods, and discussions 

 of the physico-chemical causes of their action. Of especial value to those who 

 wish to read in a short space an authoritative account of the theory and prac- 

 tice of artificial parthenogenesis is the introductory chapter, which gives a con- 

 cise but clear summary of the various branches of the subject. The author's 

 general conclusions are that all cytolytic agencies tend to cause membrane-for- 

 mation at the surface of the egg, possibly by breaking down the equilibrium of 



