254 THE JOURNAL OF BOTANY 



the fewer number of woody genera in the gamopetalous as compared 

 with the apetalous orders. This view is supported by the fact that 

 the woody Gamopetala are precisely those which are represented in 

 tertiary and cretaceous beds. The most important general results 

 are the emphasis of the uniformity of the flora of the cretaceous 

 period, as shown by the similarity of the types found in the old and 

 new worlds respectively, and the indications that this period was 

 succeeded by one of great differentiation. 



Mr. Bateson's paper is an account of the progress in the 

 study of heredity and variation which followed the rediscovery of 

 Mendel's work in 1900 in the publications of De Vries, Correns, 

 and Tschermak. The interest which this new branch of science 

 Genetics as it has been called — has aroused was strikingly shown 

 in the success which attended the International Conference held 

 last summer under the auspices of the Royal Horticultural Society. 

 The report of the Conference recently issued by the Society shows 

 even more forcibly than Mr. Bateson's essay the importance of this 



phase of biological investigation. 



Finally, Dr. Czapek's contribution is a valuable epitome of 

 the work done on the subject of plant-nutrition during the last 

 ten years. The subject-matter is systematically arranged in nine 



chapters, and occupies more than one hundred pages. 



A. B. R. 



BOOK-NOTES, NEWS, dc. 



At the meeting of the Linnean Society on 18th April, 1907, Mr. 

 James Saunders showed a series of lantern-slides of " Witches' 

 Brooms," which he explained are usually caused by one of three 

 agents: parasitic fungi (Mcidium and Exoascus), parasitic insects, 

 and gnarling. The illustrations shown were of trees affected by 

 parasitic fungi, the mycelium of which permeates in the woody 

 tissue of the diseased plants. They included Silver Fir, Norway 

 Spruce, Common Elm, Hazel, Hornbeam, Birch, Elder, Hawthorn, 

 and Wild Cherry (Primus avium). The Silver Fir was from Norfolk, 

 but all the others from South Bedfordshire and North Hertford- 



shire. Mr. J. C. 



(Ecolo 



Functions of Stolons and Cleistogamous Flowers." He pointed 

 out the advantages to the plants by the colony-forming habit, such 

 as its more certain pollination and greater power of holding its 

 own against competitors, instancing as examples Bel lis perennis, 

 Thymus Serpyllum, and Mercurialis perennis. Further examples 

 were dwelt upon in the cases of Urtica dioica, Adoxa Moschatellina , 

 and the violets Viola odorata and V. canina, where both stolons and 

 cleistogamous flowers co-operate in keeping the colonies compact. 



At the same meeting Mr. A. 0. Walker introduced the subject of 

 " The Conservation of existing Species by Constitutional or Physio- 

 logical Variation giving greater power of adaptation without per- 

 ceptible change of structure." He referred to a supposed case of 

 two healthy men going to an unhealthy climate : one proving im- 



