230 



THE PHYSIOLOGY OF TWINNING 



Torpedo, twinning in, 98 



Triplets: in chick, 77, 78, 82; 

 rarity of, 2 



Triton, 92, 175-78 



Twinning: and alternation of gen- 

 erations, 215-17; a result of loss 

 of polarity; a process of regula- 

 tion,^ 5-8; as a mode of repro- 

 duction, 206-19; causes of, 5-8; 

 causes of, in armadillo, 100-120; 

 causes of, in birds, 80-90; 

 causes of, in man, 132-34; 

 causes of, in Oligochaeta, 36^, 37; 

 definition of, i; disadvantages 

 of, 138, 139; in Amphibia, 91- 

 94; in Ainphioxus, 98, 99; in 

 birds, 73-90; in Cyclostomata, 

 98; in earthworms and allies, 

 28-37; in Elasmobranchii, 98; 

 in fishes, 38-72; in limbs, 193- 

 205; in man, 121-68; in 

 microdrilous oligochaetes, 32- 

 34; in Patiria miniata, 11-27; 

 in Reptilia, 94-97; in star- 

 fishes, 11-27; in Tiibifex tuhifex, 

 32-34; kinds of, 2; modes of, 



in Oligochaeta, 34, 35; nature 

 of, I 



Twins: budding theory of origin 

 of, 55; conjoined, in fishes, 43, 

 45 > 46; frequency of, in fishes, 

 38, 39; human, 121-68; in- 

 fluence of one on another, 25-27; 

 modes of origin, in fishes, 39-49; 

 separate, in fishes, 43, 44; 

 Siamese, 167; in tubal preg- 

 nancy, 130-32; types of, in 

 Patiria, 15-22 



Vejdovsky, F., 30, 31 

 Virchow, 58 



Weber, R. A., 30, 31 



Welch, P. S., 32-34 



Wilder, H. H., 7, 123, 126 



Willier, B. H., 80 



Windle, B. C. H., 7, 39, 51, 52, 

 61, 65 



Winslow, 74 



Wolff, C. F, 7, 74, 7S 



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