1892.] Experimental Embryology. . 589 
used to stain the egg a violet color and yet not prevent it 
developing into a blastula in which the central fluid, the 
migratory cells and the inner ends of the outer cells are violet. 
The method of inflicting mechanical injury upon sea urchin 
eggs used by the Hertwig’s resulted in breaking them in some 
cases; this means of separation has been ingeniously put in 
action by Boveri in the attempt to solve a most important 
problem. Though the perusal of this paper! does not inspire 
one with as much confidence in the strength of the conclu- 
sions drawn as the reader would wish to have in evidence 
advanced in so important a case, yet the experiments are in 
themselves very suggestive and worthy of frequent repetition. 
To prove that the nucleus is the bearer of inherited charac- 
ters we may try to combine a nucleus with a cell and see 
which or if both transmit their peculiarities. 
Using Hertwig’s method he shook eggs of the sea urchin in 
test tube till many lost the nucleus; these could be fertilized 
and developed. In this way dwarf larve, about one-fourth 
the normal size, were reared as late as the seventh day, when 
the normal larve died also. Now the great interest of these 
experiments for the present question lies in the fact that the 
eggs belong to one species and the sperm to another. 
When true bastards between normal eggs of Echinus micro- 
tuberculatus and sperm of Spherechinus granularis are formed 
the resulting larva has always a middle form between the 
larvee of these species, both in general proportions and in 
arrangement of skeletal spicules. When, however, broken 
fragments of the eggs of the first species are fertilized by 
sperm of the second we find beside some true bastards from 
the normal eggs and some small ones from nucleated frag- 
ments, some larvee exactly like those reared from pure eggs and 
sperm of the second species alone, Echinus microtuberculatus. 
These larve are regarded by Boveri as due to the fertiliza- 
tion of denucleated eggs of the other species by the sperm of 
the species they resemble. 
1Boveri. Ein geschlechtlich erzeugter Organismus ohne mutterliche Eigenschaf- 
ten. Sitzb. d. Gesellschaft f. Morphologie u. Physiologie in Munich, v, 1889, pp. 
73-80. 
