88 PATTEN. iVous Xie 
(6). Multiple embryos are produced by the formation of new 
parts which appear in a definite sequence and in a definite 
place, and in a manner the reverse of that by which old organs 
disappear by median fusion and degeneration. 
This result may be attributed either to the presence of an 
excess of formative material, or to forced drafts on the reserve 
brought about by some unknown internal conditions: If the 
former supposition were correct, there is no obvious reason why 
the additional parts should not be permanent acquisitions. We 
cannot assume that such an arrangement of parts as we see in 
multiple embryos is necessarily fatal to their codrdination, be- 
cause the large numbers of double embryos of all kinds that 
have reached advanced stages of development, as is well known, 
would testify to the contrary. On the other hand, our next 
fact (7), that multiple embryos almost immediately degenerate 
by median fusion arid antero-posterior degeneration, shows, it 
seems to me, that ¢here zs no production of new “ formative 
material,’ but a misdirection of that already existing. There 
7s in Some way the dividing up of the sum total of formative 
material so that it crystallizes out along two or three lines 
znstead of one. 
The fact that these new centres start out all right but soon 
begin to degenerate in the same way that poorly endowed 
single embryos do, shows that there was not enough formative 
material to go round ; that multiplying the formative centres 
simply cuts off specialization and longevity at the other 
end. 
This supposition is still further supported by the next two 
facts, namely (8) : 
The individuals of triple embryos recently formed differ 
greatly in size and in the amount of degeneration, and (9) 
In old triple embryos the individuals are more nearly alike. 
Before we consider these two points further, let us assume for 
a moment that in the formation of multiple embryos there 
has been, figuratively speaking, a forced growth producing 
material faster than it can be differentiated, and that the point 
of greatest differentiation tension is at the oldest point, where 
the most growth and specialization had already taken place. 
OO Es 
