iqiq] currext literature 151 



regularly more successful than foreign pollen. "If this is true, crossing is 

 without effect until .... the union of the male and female nuclei." In 

 certain of the inbred strains the author records a marked tendency toward 

 dioecism. Some of the inbred strains which maintained the highest ovule 

 development were the most deficient in pollen development, while the exact 

 reverse was true in other strains. 



In his general discussion the author suggests that the advantages of hybrid 

 vigor may have played their part in the rise of the sporophyte generation. 

 Certainly if his interpretation of the phenomenon is correct (the reviewer 

 believes it is), the advantages of hybrid vigor would be impossible in the game- 

 tophyte generation with its haploid equipment. — ^Merle C. Coulter. 



Perennating fruit of Cactaceae. — Johnson* has investigated the remarkable 

 behavior of the fruits of certain Cactaceae, using Opuntia fulgida as material. 

 The fruits of these Cactaceae remain attached to the plant and actively growing 

 for several or many years. The fruit of 0. fulgida not only remains attached, 

 unripened, and steadily growing, but the seeds are never shed from the fruit. 

 In addition to this, the matured fruit, or even the ovary of the unripened 

 flower, may give rise to secondary flowers and so to other fruits. As many as 

 4 or 5 generations of flowers and fruits may thus be formed in a single season. 

 If a mature fruit falls on moist soil, it may develop adventitious roots and shoots 

 and thus initiate a new plant. 



The early development of the ovary resembles that of a young vegetative 

 joint, and is entirely stemlike in appearance, with its evanescent leaves, 

 tubercles, and axiUary areoles. It is evident, for many reasons, that the whole 

 outer wall of the ovary and fruit is morphologically of stem origin. The 

 continuous formation of flowers is remarkable, as indicated by the following 

 description: "From the axillary buds, or areoles, of the primary flowers that 

 open in May, arise secondary flowers which open in June. From areoles of 

 these, in turn, tertiary flowers open in July, and on the latter quaternary 

 flowers bloom forth in August." 



The contribution contains much interesting material that cannot be 

 included in a brief review, but it all presents the unusual habits of a remarkable 

 group of plants. — J. M. C. 



Alaria. — Yendo^ has published a monograph of Alaria which is remark- 

 ably full in its details and noteworthy in the quality of its plates. The intro- 

 ductory pages deal with the morphology of the genus, every region of the plant 

 being considered, and the development and life history presented, so that the 



^Johnson, Duncan S., The fruit of Opuntia fulgida. A study of perennation 

 and proliferation in the fruits of certain Cactaceae. Publ. Carnegie Inst. pp. 62. 

 pis. 12. 1918. 



9 Yendo, Kichisaburo, a monograph of the genus Alaria. Jour. Coll. Sci. 

 Univ. Tokyo 43:1-145. pis. iq. 1919. 



