182 BOOKS AND CURRENT LITERATURE 



relation to botanical information familiar to the student is pointed out. 

 Frequent diagrams illustrate the text but half-tones are avoided. Quo- 

 tations in large and small type, chiefly from East, are used freely 

 throughout. The latter part of the book is less elementary than the 

 first and the method of treatment more like what one would expect if 

 the title had been "Problems in Plant Genetics." The chapter on 

 "Inheritance in Gametophytes," for example, contains an interesting 

 discussion of a topic largely neglected by more ambitious text books of 

 genetics. The professional genticist might expect in a text of this size 

 a somewhat greater reliability in details and a more extended discussion 

 of the established facts with a less extended discussion of problems 

 suggested to a botanist. He will, however, find the book stimulating 

 reading. Botany, in fact, is the fundamental science. It is unfor- 

 tunate that there have been some who have seemed to act upon the 

 belief that forestry, plant pathology and plant genetics are subjects 

 unrelated to botany. Coulters' Plant Genetics will be found of value 

 in advanced departments of botany like that in the University of 

 Chicago. — A. F. Blakeslee. 



Proliferation in Cacti. — The peculiar behavior of the fruits in 

 certain species of cacti has been investigated by Johnson, 1 with par- 

 ticular reference to proliferation in Opuntia fulgida. The fruits of 

 Opuntia and two closely related genera are unlike those of all other 

 flowering plants in the possession of abortive leaves with functional 

 axillary buds. In Optunia fulgida the withering stamens and petals 

 are separated from the ovary by a definite abscission layer, but the 

 maturing of the seeds fails to produce any of those changes in the fruit 

 which are almost universal among higher plants: there is no ripening 

 nor change of color, there is no form of dehiscence, there is no separa- 

 tion of the fruit from its parent stem, and there is frequently a continu- 

 ation of growth. The axillary buds, or areoles, of the fruit regularly 

 produce trichomes and nectaries, frequently produce flowers, and in 

 very rare cases give rise to vegetative shoots. The persistence of the 

 fruits, and their proliferation from one to four times a year, results in 

 heavy pendent clusters. These are eagerly eaten by cattle but reach a 

 length of 12 to 18 inches on undisturbed plants. The early develop- 

 ment of the ovary in Opuntia fulgida is found to resemble that of a 



Johnson, Duncan S. The Fruit of Opuntia fulgida; a study of perennation 

 and proliferation in the fruits of certain Cactaceae. Carnegie Inst. Wash. 

 Pubn. 269. Pp. 62, pis. 12. 1918. 



