Secondary Coaptation in Grafts 129 
point of their union. “This is an example of the phe- 
nomenon observed also in all the other organs, that 
after the growing together of two sections of unequal 
size and form, the uneven character of the union, present 
at first, disappears and gradually a smooth connection 
of the surfaces is established.” °° 
The union of the corresponding organs of the two 
fragments is quite intimate: for example in the case 
which we have just cited, longitudinal sections of the 
two united medullas showed that the fibers of the white 
substance of the medulla spinalis went over continuously 
into those of the white substance of the elongated medulla 
oblongata.°? 
Among the experiments of Born, those upon the 
artificial production of double monsters are especially 
remarkable. They were obtained by joining two tadpoles 
together in the most diverse ways. In the case which 
we now report he cut away from each of two tadpoles 
the upper part of the ventricles of the brain and joined 
the two cut surfaces together so that both the tails and 
the bellies of the two tadpoles constituting the double 
monster were directed in opposite ways. Here also, there 
took place, in so far as the two tadpoles developed, a 
complete union so that after sometime there could not 
be perceived any transition stage between the surfaces of 
the corresponding organs which were united together. 
“It is impossible to believe,” remarks Born in this 
connection, “that in placing these two tadpoles one upon 
the other, the small ventricular clefts and the external 
walls of the two brains could be applied exactly one upon 
°G Born: Uber Verwachsungsversuche mit Amphibienlarven. 
P. 53—54. 
°7G_ Born: Uber Verwachsungsversuche usw. P. 56. 
