450 



NATURE 



[June io, 1920 



deals fully with the celebrated Hantzsch-Bam- 

 berg-er controversy, which was maintained for 

 several years. The author has himself formulated 

 a theory of the constitution of diazonium salts 

 which, with a modification sugg-ested by the re- 

 viewer, is sufficiently elastic to account for the 

 properties of aromatic diazo-compounds and also 

 for the existence of a rapidly increasing- group 

 of heterocyclic and non-aromatic diazo-derivatives. 

 A new chapter on the latter group has been added 

 to this second edition of a unique monograph. 



G. T. M. 



Ancestral Studies of Compositae. 



The Origin and Development of the Compositae : 

 Thesis approved for the Degree of Doctor of 

 Science in the University of London. By Dr. 

 James Small. (New Phytologist Reprint, 

 No. II.) Pp. xi + 334 + 6 plates. (London: 

 William Wesley and Son, 1919.) Price 15s. 

 net. 



THERE is perhaps a tendency among system- 

 atic botanists to fight shy of the Compositae, 

 on account largely of the enormous size of the 

 family and the difficulties of properly classifying 

 its members. Those, however, who once succeed 

 in passing these lions in the path soon become 

 enthusiastic students of the group, and Dr. Small 

 is no exception to this rule. His contribution to 

 the investigation of the origin and development 

 of the family is by far the most important that 

 has appeared for many years. 



After a general discussion of previous literature, 

 in which the most important names are those of 

 Cassini and Bentham, the author goes on to deal 

 with the various morphological and ecological 

 features of the family one by one, considering, 

 for example, the pollen-presentation mechanism, 

 the corolla, the pappus, the involucre, the recep- 

 tacle, the phyllotaxis, and the fruit dispersal From 

 all of these, similar general conclusions are 

 drawn, to the effect that the Senecioneae are the 

 most primitive type of the family, and that from 

 them, directly or indirectly, and ultimately from 

 Senecio itself, as the basal genus from which the 

 Senecioneae arose, there sprang all the other 

 tribes and genera of the family. This is then 

 very strikingly confirmed by a study of the geo- 

 g-raphical distribution, which shows what would 

 be expected upon this theory of mutational origin, 

 and upon the hypothesis of age and area, which 

 is likewise adopted. It is shown that the dis- 

 tribution of Senecio (the oldest genus) is the 

 widest of all, and that of other tribes and genera 

 less and less in proportion to their lesser age. 

 NO. 2641, VOL. 105] 



Senecio is supposed (and the evidence is fairlv 

 clear) to have arisen from the Siphocampylus 

 group of Lobelioideae, and probably in the Bolivian 

 highlands after the upheaval in the Cretaceous 

 period had provided available land above the 

 limit of trees. Once formed, its pappus fruit 

 and the great area of open land available in the 

 mountain chains which with few breaks run all 

 round the world enabled it to spread rapidly over 

 America, Asia, Africa, and Europe. 



In the final chapter an interesting sketch is 

 given of an hypothetical eVolution of the Com- 

 positae from Senecio, based upon the various con- 

 clusions drawn in the course of the work, summed 

 up largely in a diagram on p. 297, which illus- 

 trates this evolution in time and space. The 

 second great genus to evolve is supposed to have 

 been Gnaphalium (from which the Inuleae are 

 descended), then Spilanthes (Heliantheae), Solid- 

 ago (Eupatorieae and Astereae), and so on. The 

 whole is a striking- and interesting illustration of 

 the way in which our whole outlook upon phylo- 

 geny has been altered by the acceptance of the 

 modern theories of evolution and geographical 

 distribution. 



In the course of the work many minor points 

 are further elucidated, such as irritability in the 

 pollen-presentation mechanism. Good reasons are 

 brought forward for supposing the pappus to be 

 of trichome nature, and by an ingenious 

 mechanism the dispersal of the seed was studied, 

 and it was shown that a very slight wind was 

 sufficient to keep the seeds aloft in sufficiently dry 

 air, so that there is no need for land bridges to 

 explain the distribution. Many other points are 

 also dealt with, for which reference must be made 

 to the original. 



Our Bookshelf. 



Monarch: The Big Bear of Tallac. By Ernest 

 Thompson Seton. Pp. 215. (London : Con- 

 stable and Co., Ltd., 1920.) Price 75. 6d. net. 



This is a composite picture of a grizzly bear, 

 or, more exactly, the personality of one remark- 

 able bear still living in prison has been credited 

 with the adventures of several of his kind. Begin- 

 ning with the growth and education of the cub, 

 the book tells the story of many ups and downs, 

 such as the first sheep-stealing, the escape from 

 the forest fire, the circumvention of the hunters ; 

 the affair of the ten-gallon empty sugar-keg with 

 the delicious smell, into which the bear thrust 

 his head ; and the final capture (by means of 

 drugged honey) of an adventurer with many 

 aliases. Mr. Thompson Seton is a fine raconteur, 

 but we wish he had put a little more stuffing into 

 the book ; and his literary facility sometimes gets- 



