No. 2, December, 1921] HORTICULTURE 87 



of 4S articles on variation and heredity which appeared in scientific journals during the years 

 1897-1914 inclusive. All articles are repaged, but complete citations are given. — Geo. H. 

 Shull. 



549. Woods, Frederick Adams. Twins prove the importance of chromosomes. Jour. 

 Heredity 10: 423-425. 1919. — The author states that identical twins alone have the same kind 

 of chromosomes because early in embryonic life there occurs an almost absolutely precise 

 division of the chromosomes so that 2 individuals develop, controlled by similar determiners. 

 The importance of these determiners is proved by the extreme resemblance of identical twins, 

 thus demonstrating also the lack of importance of the environment. In a sense, environment 

 is all-important, for growth depends upon nourishment, oxygen, and warmth; but these are 

 customary and expected. Identical twins show that ordinary differences within the uterus of 

 the mother, home life, school life, and adult life do not modify greatl}' the control of the chro- 

 mosomes. On the other hand, non-identical twins are not similar although having the same 

 similarities and differences that are found in the case of identical twins. Great changes in 

 environment may cause considerable modification in individuals, but great changes are not 

 usual. The physical and mental differences observed in one's friends are due to differences 

 traceable to the chromosomes. — H. II. Laughlin. 



550. Wright, Sew all. A case of heredity vs. environment. [Rev. of: Key, Wilhbl- 

 MiNE E. Heredity and social fitness: a study of differential mating in a Pennsylvania family. 

 Carnegie Inst. Washington Publ. 296. 102 p., 2 diagrams. 1920 (see Bot. Absts. 9, Entry 

 239).] Jour. Heredity 12: 110. 1921. 



HORTICULTURE 



J. H. GouRLBT, Editor 

 H. E. Knowlton, Assistant Editor 



(See also in this issue Entries 391, 392, 400, 433, 435, 443, 490, 527, 693, 702, 719, 726, 727, 



740, 773, 776, 778, 789, 839, 855) 



FRUITS AND GENERAL HORTICULTURE 



551. Anonymous. [Rev. of: Copelaxd, E. B. The coco-nut. 2nd ed., xvi + 225 p., 

 2H illus. MacMillan & Co.: London, 1921.] Sci. Prog. [London] 16: 160. 1921. 



552. Anonymous. [Rev. of: Whymper, R. Cocoa and chocolate: their chemistry and 

 manufacture. Rev. ed., xxi + 368 p., 16 pi., 38 fig. J. & A. Churchill: London, 1921.] Sci. 

 Prog. [London] 16: 160. 1921. 



553. Atkins, W. R. G. Natural indigo. Sci. Prog. [London] 16: 56-70. 1921.— A brief 

 general outline is presented of the field covered in the study of natural indigo. More detailed 

 accounts of the work may be found in the Reports of the Sirsiah Indigo Research Station and 

 in the Botanical Institute, Pusa. The best varieties to grow, proper methods of fertilization 

 and cultivation, best known means of obtaining the indigo from the plant, and the demands 

 of the markets of the world have all been subjects for considerable research. Before the World 

 War natural indigo was being rapidly replaced by a synthetic product. The great value of 

 the plant in adding nitrogen to the soil through the agency of the legume bacteria, and the 

 manurial value of the fermented plants from which the indigo has been removed make it pos- 

 sible to produce the indigo quite cheaply. The plant is not subject to diseases known to be 

 produced by micro-organisms; but a wilt disease, thought by some to be due to a deficiency of 

 available phosphates in the soil, occurs. — J. L. Weimer. 



554. Birmingham, L. E. Cooperative organization for fruit growers. Trans. Indiana 

 Hort. Soc. 1919: 45-48. 1920. — A suggestive account is presented of the organization and 

 activities of a fruit growers union in the Sturgeon Bay region of Wisconsin. — Max W. Gardner, 



