1895.] Embryology. 591 
again if kept close together. This led to a series of experiments that, 
at the time of publication, furnished the results enumerated below. 
He used larvee that were ready to escape from the egg jelly or those 
that had just escaped. They were put into 6% solution of sodium 
chloride and cut across with scissors or a scalpel into an anterior and 
posterior half. The pieces were at once brought together and held in 
place by various means till they grew together completely. Subse- 
quently they were transferred to a fresh supply of the salt solution. It 
was found to be easy to get two tail pieces to unite, since the cilia that 
normally move the animal forward would push the two tails toward one 
another. With other pieces various artificies were necessary to prevent 
the ciliated action or the muscular contraction moving the wounded 
surfaces apart before union had taken place. 
1. When the tail ends of two tadpoles of Rana esculenta are placed 
with the cut ends together, they unite in twenty-four hours quite com- 
pletely, so that there is little external evidence of the line of fusion. 
These joined tails live for eight days and increase in length; they then 
degenerate and become dropsical. 
The union may be. made direct with the dorsal and ventral sides 
continuous in the two, or inverted with the dorsal of one continuous 
with the ventral side of the other. When very long pieces are taken 
a heart may develop in each, while in seven days there is an increase 
in length, for the two, of 2.9 mm. from a length of 15.6 mm. 
It is also possible to unite such a long posterior part with a shorter 
posterior part; then the head of a larva is replaced by the tail and 
belly of another growing forward in its place. 
2. The anterior ends of two larvæ may be made to unite. This suc- 
ceeds more readily with the younger stages. Here again the union 
may be direct or inverted. In one case'of the latter method of fusion, 
two that had been cut across in the region of the liver, remained united 
for fourteen days, during which time much differentiation took place 
in each head. ; 
In the larvæ of the newt, triton, union of anterior pieces was affected, 
but this was less complete than in the case of the frog tadpoles. 
3. Complex unions of two larvæ may result when the cuts are not 
quite complete and the two pieces of each remain connected by a slen- 
der bridge of tissne; the two pieces may be folded back side by side, 
and then pushed against the similar pieces of the other larva. The 
opposite ends of two larvæ may then fuse together while still remain- 
ing attached to their own proper terminations. 
