172 THE PLANT WORLD. 



herliarium species, prepared either from plants in their native 

 haunts or from those in collections, are in man}' instances unsat- 

 isfactory for study, because they can, at the best, be but frag- 

 mentary. Herbarium specimens supplemented by flowers and 

 fruit preserved in formalin, b}- pho'tographs of the flowering" plant 

 and b\' colored drawings of the flowers, are satisfactory taken in 

 connection with the living plant, and if such series of material of 

 each species can be brought together, it will ultimately lead to a 

 far better understanding of this very interesting family. 



The preparation of manuscripts for the " North American 

 Flora,"" now in course of publication by the Xew York Botanical 

 Garden, through the aid of. the David Lydig Fund, bequeathed 

 by Judge Charles P. Daly, has made it very desirable that a more 

 accurate knowledge of the cactuses of North America should be 

 obtained within the next few }"ears, and the bringing together of 

 the material along the lines outlined has been undertaken in coop- 

 eration with Dr. J. N. Rose, of the U. S. National Museum. 

 Greenhouses at Washington and at New York have been set aside 

 for the housing of the plants, and exploration of the cactus-}ield- 

 ing regions of North America, including the West Indies and the 

 continent south to the Isthmus of Panama, is going forward and 

 will be continued as rapidly as means for it become available. — 

 Professor N. L. I'ritton, in the Journal of the Horticultural So- 

 ciety, N. Y., A]3ril, 1906. 



REVIEWS. 



The Principles of Heredity. By G. ARCHiP.ALn Reid. Second 

 edition. 8vo. Pp. xiii + 37CJ. London: ChajMiian & Hall, Ld. 

 The second edition of this work difl:'ers from the first chiefly 

 in the addition of two appendices. Appendix 1! deals with 

 " Mendel's Laws and the Mutation Theory of Evolution." The 

 first thing to arrest the attention of the botanist is the statement 

 in the third sentence of this appendix tliat, " The flower of this 

 plant (the pea, Pisuiii) is not a(la])ted to receive the visits of 

 insects . . ." And this not onh- in tlie face of the evidence 



