334 XOTICES OF BOOKS. 



intimately the outward form and tlie intra-cellular phenomena are 

 related to physical laws such as those governing surface-tension 

 and those forces wliich are in opposition to it. The account of 

 mitosis is based on the provisional assumption that the pheno- 

 mena are analogous to, if not identical with those of a bipolar 

 electrical field. In the groupings of the daughter-cells in a 

 segmenting egg as well as in the arrangement of the cell-bound- 

 aries in the meristem of an apical bud or developing sporangium, 

 the author shows that the interpretation may be found in the 

 principles which govern space-partitioning in minimal areas, and 

 that we are but dealing with concrete instances of a subject, the 

 theory of which has fascinated mathematicians since the days 

 of Leibnitz and Euler. " Examples of these various arrangements 

 meet us at every turn, and not only in cell-aggregates, but in 

 various cases where non-rigid and semi-fluid partitions (or 

 partitions that were so to begin with) meet together. And it 

 is a necessary consequence of this physical phenomenon, and of 

 the limited and very small number of possible arrangements, 

 that we get similar appearances, capable of representation by 

 the same diagram, in the most diverse fields of biology." In 

 Chapter IX the spicular skeleton of sponges is dealt with, and 

 a particularly interesting discussion on the conformation of the 

 delicate and complex siliceous skeleton occurring amongst the 

 Radiolaria, which have such a wonderful and unusual appearance 

 of geometrical regularity. Prof. Dendy's presidential address to 

 this Club on the "Chessman" spicules in the genus Latruncula 

 and his paper in collaboration with Prof. Nicholson read at the 

 Royal Society in June, on the ringed spicules of an allied genus, 

 were published too late for reference by the author. The results 

 obtained in this research show that the rings of silica are deposited 

 at the nodes of a vibrating rod. Prof. D'Arcy Thompson would 

 have seen in these results another instance of the advantages 

 of mathematical methods. The general and mathematical pro- 

 perties of the logarithmic spiral are described, and the application 

 of these to the spirals of molluscan shells, in a very attractive 

 chapter, attractive not only for its matter but also for its beautiful 

 illustrations. 



The micro-biologist will, however, pass onto the treatment of 

 the spiral shells of the Foraminifera. If the author's interpreta- 

 tion of the form and mode of growth of the foraminiferal shell be 



