230 The American Naturalist. [March, 
a thousand of them. The result was always the same. All 
genuine bastards, with not a single exception, represent both in 
the shape of the body as well as in the skeleton an almost 
exact middle form standing between the two parents. This is 
a new well defined form, and is always as such to be recog- 
nized and cannot be confused with either of the two parent 
larval forms. Fig. 3, A and B, which shows such a genuine 
Bastard larva, illustrates, as compared with figs. 1 and 2, 
this law better than many words could possibly do. 
The result is otherwise if we shake into pieces the Sphere- 
chinus egg before the entrance of the Echinus-spermatozoon. 
Certain of the eggs remain intact after the process, and these do 
give the genuine bastard form (Fig. 3). These -are those 
formed from nucleated pieces, but another portion of the crossed 
H i 
Fig. 4. Dwarf bastard larva of Echinus g and Spherechinus Q (fragment) of pure 
Echinus type. 
larvæ agree entirely with the simple larva derived from 
the egg and spermatozoon of Echinus microtuberculatus (Fig.1)- 
These must have been produced chiefly from enucleated frag- 
ments. (Fig.4 A and B.) 
That this is the correct interpretation is more clearly demon- 
strated by rearing in isolation the enucleated pieces. * My 
