236 THE AMERICAN NATURALIST. [Vor. XXXIV. 
anatomy of the shining bodies in Porichthys. He concludes that 
these are true phosphorescent organs. 
Thus far no specimens have been found to be luminous in the 
aquarium, and light has not been developed through electric stimu- 
lation, or by excitement through ammonia. Bom 
Absence of Retinal Pigment in the Dogfish. 
the retina of the common dogfish (Mustelus vulgaris) Schaper! has 
made the noteworthy observation that the retinal pigment cells, 
which in most vertebrates are loaded with dark pigment granules, 
are in this animal absolutely devoid of such particles. P. 
Pupa-Grafting in Moths. — The method of grafting young ani- 
mals, as devised by Born for tadpoles, has been applied by Cramp- 
ton? to the pupz of moths. An injured pupa at best regenerates 
sufficient integument to cover the wound. Parts of two longitudi- 
nally split pupa joined in natural proportions failed to unite, but 
anterior and posterior portions cut at any level united. Compounds 
slightly smaller than normal or enlarged by the insertion of a ring 
failed to coalesce. Fragments grafted on whole pupz formed exactly 
those portions they would have formed had they remained on the 
original pupa. Pupz are easily united sidewise or endwise, but in 
these, as in all other cases, the union is that of the integument and 
superficial parts only. The results of these experiments on the colors 
of different species are especially interesting. When individuals of 
two species having different colors were united so that their hamo- 
lymphs mingled, the outcome was almost always a double animal 
whose colors were normal. The same result was obtained from 
united males and females in species with differently colored sexes. 
The colors are probably produced, as a rule, through the action on 
the hemolymph of a localized internal factor such as the “ ferment " 
cytoplasm assumed by Mayer. P. 
Amitotic Followed by Mitotic Cell Division. — The observa- 
tions of Gerassimoff, that cooling would convert the mitotic division 
of Spirogyra cells into amitotic, and of Pfeffer and Nathanson, that a 
lSchaper, A. Die nervósen Elemente der Selachier-Retina in Methylenblau- 
praparaten, Festschrift zum siebenziegsten Geburtstag von Carl von Kupffer, 10 pp» 
2 Crampton, H. E. An Experimental Study upon px mit de Archiv für 
Entw.-mech., Bd. ix, pp. ple? Pls. XI-XIII, 1899. 
