80 The American Naturalist. [January, 



The converse bastards also show great variation in the skeleton. 



Boveei 9 republishes, is an amplified form with many new illustrations, 

 his remarkable work on the cross-fertilization of enucleated fragments 

 of sea urchin eggs, translated in the American Naturalist March 1, 

 1893. After considering the opposing results obtained by Morgan and 

 bySeeliger the author still maintains that he has shown that a larva 

 may be obtained from a piece of an egg without any nucleus and sperm 

 of another species and that such a larva has none of the maternal char- 

 acters but only those of the male parent, thus showing that the nucleus 

 may transmit characters but that egg cytoplasm alone cannot do so. 



The evidence for his conclusions is, however, of an inferential 

 nature and a cautious jury may well hesitate before convicting Boveri 

 of having deprived the cytoplasm of its share in the affairs of heredity. 



The evidence as he now presents it seems to be about as follows. 



1. When at Naples in 1889 he shook a lot of sea urchin eggs, Echinus 

 microtuberculatus in a testtube many were broken into pieces of various 

 sizes, with or without nuclei ; when this collection was treated with 

 sperm of the same species larvte of all sizes down to A of the normal 

 were found. 



2. When pieces that contain no nucleus, as far as could be seen 

 under the microscope, were isolated and fertilized with sperm of the same 

 species they developed into dwarf larvae. 



3. When the normal eggs of Sphrcerchinus granularis are treated 

 with the sperm of Echinus microtuberculatus some few bastards result. 

 In Boveri's original experiment all these bastards were half way between 

 the larvae of the parent species, both in external form and in the skele- 

 ton, which were very different in each pure larvae form. 



4. When the eggs of E. microtuberculatus are shaken and treated 

 with sperm of the same species the larvae present many abnormalities 

 and some may have characters resembling those of another species. 



5. When shaken eggs of S. granularis are treated with sperm of E. 

 microtuberculatus large and small larvae are formed ; some few of the 

 small ones, only a wery few, 10 or 12 in all, were entirely of the 

 Echinus or father type. 



6. It was observed that the nuclei in any given area of a larva 

 formed from a nonnucleated piece of Echinus egg and the sperm of the 

 same species were, on the aver<iye, -mailer than the nuclei in the corre- 

 sponding area of a smaller larva formed from a nucleated piece. 



7. The above few bastard larvae of pure Echinus type had, on the 

 average, smaller nuclei than similar larvse of type intermediate between 

 the two crossed parent. 



9 Idem, Oct. 22, 1895, pps. 394-441. 



