The Morphology of Cosmobia 439 



the lower animals in distinction from those of man. Since in the pres- 

 ent paper, I have emphasized quite a different sort of comparison, 

 that between monsters that represent different grades in the same cos- 

 mobiotic series, a phase of the subject to which I have given the name 

 Cosmobiogenesis, the distinction between the two must be kept in mind. 



Finally in this review of recent literature, which makes no pretense 

 at being complete, I may mention a school whose ideas concerning the 

 genesis of double monsters are definite, and decidedly different from 

 those promulgated in this paper. This is the school which looks upon 

 most or all forms of double monsters as caused by an attempt at regenera- 

 tion following a fetal trauma. 



Thus ToRNiER^^ speaks of the "Stammindividuum" and the "Ueber- 

 zahliges Individuum," a set of terms that receive their best application 

 in the case of those forms of double monsters in which one component 

 is considerably smaller than the other, and it is precisely such cases that 

 this author seems to emphasize. In the cases of equal components, 

 especially in a typical case of duplicate twins, this theory does not 

 prove satisfactory, and this author is careful not to make his claims 

 for '^superregeneration" too sweeping. Thus in Schwalbe^s Jahres- 

 Ijericht for 1902, in referring to a paper which I have unfortunately 

 not been able to obtain, the referant says of him, "mindestens einen 

 Teil der Doppelbildungen will T. ebenso auf Superregeneration zuriick- 

 fiihren'^ a statement which suggests a probable difficulty with sym- 

 metrical and equal diplopagi. Tarnani/^ whose conclusions rest upon 

 the anatomical study of 21 double monsters, 5 being mammalian, the 

 others birds, proposes a form of the theory which gets around this 

 difficulty, but only by assuming a theory for which there is no support 

 in observed fact, namely, that double monsters are produced by a trauma 

 which splits the vertebral column longitudinally and medially. After 

 this assumed splitting, which may involve either end to any degree, or 

 both ends, there is a regeneration of the parts lacking to either half. 

 If, for example, such a splitting involves a girdle the separated right 



''■ToKNiER. G. [Numerous articles upon pxperiuientally produced hyper- 

 dactylism, bypermelism, double tails, etc., mainly in Zool. Anzeiger from 1897 

 to the present time. Of these cf. especially "Neues iiber die natiirliche 

 Entstehung und experimentelle Erzeugung iiberzahliger und Zwlllingsbiia- 

 ungen" in Zool. Anzeiger, 19 Aug., 1901, pp. 468-504. See also bis paper fn 

 the Berichte des 5ten Zool. Kongresses, Berlin, 1901.] 



''Takts'am. I. K. Yro^lstva shivotuiech ; (3) K'morphologic dvoiniccli 

 yrodstv. Zool. Cabinet of the agricultural and forestry institute of Novo- 

 Alexandria, 1906. 



