SHORT NOTES 333 



All the other characters point with equal certainty to E. roseum as 

 being the second parent ; notably the numerous small gland-tippes 

 hairs on the shrunken shortened capsules, the frequently ^j/«^- petals, 

 and the patent, distinctly stalked, neat, oval leaves. I have often 

 sought for the hybrid in W. Surrey, where these two species grow 

 together not uncommonly, but withovit success. Dr. Dral)ble records it 

 from Derb^^shire ; I have not seen a specimen. It appears to be very 

 uncommon on the Continent ; Prof. Haussknecht wrote to me that 

 Schmalhausen's plant from Gostilizy, near Petersburg (1875), so 

 named in the Monograph, p. G5, proved to be SJ. hirsutumxparvsi- 

 fiorum ; but that true E. hhsutum X roseum was found at Miihl- 

 hausen, near Jena, about the year 1886. — Edward S, Marshall. 



KEVIEW. 



Plant Genetics. By John M. Cotjlter and Merle C. Coulter. 

 8vo, pp. ix, 214, with 40 text-diagrams. University of Chicago 

 Press, July 1918. Price «l-50 net. 



Prof. John Coulter, the Head of the Department of Botany, 

 Chicago University, is well known to English students as the joint 

 author of a classic work on the Morphology of the Seed-plants; his 

 co-author in the present work is Instructor in Plant Genetics in the 

 same University. The aim of their book is to supply a general 

 authoritative text which shall form an easy introduction to plant 

 genetics. As stated on the temporary cover, to read the literature 

 of this subject with understanding requires first an appreciation of 

 the point of view and method of attack of the working geneticist, and 

 secondly an acquaintance with certain classic investigations which are 

 matters of common knowledge among geneticists. This volume 

 provides these two things, and at the same time is easy reading for a 

 student who has an elementary training in botany and the theories of 

 evolution. There has been no attempt to give a complete presentation 

 of modern genetics, and as a reference book it is admittedly inadequate, 

 much representative material having been omitted and only enough 

 bibliography given to put the student upon the trail. The authors 

 have succeeded in giving a readable and connected account of a branch 

 of biological study which is not an easy one, and in which moreover 

 much must be taken for granted, partly no doubt because it is 

 at present only in an early stage of develojiment. At the same time 

 they make it clear that there are great possibilities in its further 

 development towards the understanding of the fundamental principles 

 of evolution. 



A short chapter is devoted to a discussion of earlier theories of 

 heredity. Darwin's theory of pangenesis asserted that the indi- 

 vidual cells and organs of the whole organism are represented in every 

 germ-cell and bud by definite material particles. These multiply by 

 division and at cell-division pass on from the mother-cells to the 

 daughter-cells. This theory is in keeping with the present point of 

 view, but failed to obtain acceptance owing to its association Avith 

 the transi)ortation hypothesis, Avhich was an attempt to account for 

 certain facts which seemed to indicate the inheritance of acquired 



