ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 825 



Xanthoehroism of Parrots.* — C. F. W. Krukenberg has studied f 

 chemically and spectroscopically the different pigments that he ex- 

 tracted from the feathers of birds. Most of these are red or yellow ; 

 green pigments are rare. A. B. Meyer has also taken up the subject, 

 a propos of a Moluccan parakeet (^Eclectus polycMonis), which, though 

 certainly undomesticated, had some citron-yellow plumes where the 

 usual colour is green, blue, or black — a peculiarity which can be pro- 

 duced artificially upon birds kept in captivity. Thus the Indians of 

 South America pluck out the feathers of parrots, and treat the new 

 roots with the milky secretion from the skin of a small batrachian, 

 with the result that the new growth of feathers is yellow. The 

 aborigines of Gilolo, by giving animal food to Lorius garrulus, trans- 

 form its plumage into that of the Lori rajah. The natural colour 

 returns after an exclusively vegetable diet. The green colour so 

 common in birds is due to an admixture of a yellow pigment (psittaco- 

 fulvine Krukenberg) with a dark-brown one ; and Krukenberg states 

 that no blue, white, or green pigment can be found among the parrots. 

 He believes that all the darker pigments are derived from one sub- 

 stance, probably identical with coriosulphurine, which is thus the 

 most widely spread pigment in birds' feathers. 



Origin of the Individuality of Higher Animals.J — H. Fol dis- 

 cusses the question of the physiological origin of the individual, and 

 what is the first fact of personality. To obtain the desired criterion 

 we cannot content ourselves with following the normal succession of 

 embryological events, but must have recourse to experiment and to the 

 observation of pathological processes. The study of double monsters 

 derived from the development and gradual union of two embryos com- 

 prised within the same yolk may lead to some suggestions. 



In answer to the question, what are the factors which determine 

 the formation of one or more embryos at the expense of a single yolk ? 

 the author gives an account of some observations chiefly conducted on 

 the ova of Strongylocentrotus lividus, which appear to be especially 

 well adapted for investigations of this kind. One or two spermatozoa 

 may enter the ovum without affecting the course of its development ; 

 if three do so, the future of the egg is endangered ; the spermatozoon 

 does not act as an individual, it merely represents a certain dose of 

 nuclear substance. 



Ova which are improperly matured or altered allow of the entrance 

 of a much larger number of spermatic filaments ; the author, in his 

 experiments, has subjected perfectly fresh and mature ova to a momen- 

 tary narcotization by carbonic acid ; these will receive three or four 

 spermatozoa each; at first there are no distinct indications of any 

 deviation from the ordinary method of development ; but when the 

 first act of fission is about to be effected, a complex caryolitic figure — 

 a triaster, a tetraster, or two parallel amphiasters, appear in the place 



* SB. K. Preuss. A.kad. Wiss. Berlin, 1882, pp. 517-24. See Amer. Natural., 

 xvii. (1883) p. 891. 



t Vergl. Physiol. Stud., ii. (1882) pp. 213-20. 

 X Comptes Kendus, xcvii. (1883) pp. 497-9. 

 Ser. 2.— Vol. III. 3 K 



