108 Cc. V. MORRILL 
what precautions were taken to avoid this. The writer using 
the American salamander, Diemyctylus viridescens, obtained 
similar results some years previous to Kurz’s report but for 
various reasons they were not published.? Recently a new series 
of experiments were made to work out the histological details 
of the process and to determine how it differs, if at all, from’ 
regeneration after injury to remaining bones or cartilages. In 
addition, a number of more complicated operations were made 
to analyze further, if possible, the extent and power of regenera- 
tion after losses not usually met with in nature. 
MATERIAL AND METHODS 
A large supply of adult Diemyctylus was obtained through the 
kindly assistance of Prof. A. Treadwell, of Vassar College. Since 
many of these animals were in a weak, semi-starved condition 
when brought to the laboratory, they were kept for a month in 
glass aquaria before using and were fed on fresh liver. Under 
these conditions the animals became very vigorous, and with- 
stood the operations well. All operations were done under 
narcosis. At first ether was used, but this, owing to its irritating 
effect on the skin and to a certain percentage of mortality which 
followed its use, was soon discarded. Much better results were 
obtained by using a solution of chloretone, of 1: 2000, in which 
the animals were immersed. This acts very gently. After 
swimming around rapidly for a few minutes, the salamanders 
slowly come to rest and in about ten minutes are completely 
nareotized. The animals recover readily, though sometimes 
slowly after this treatment. There is no irritation of the skin 
and no mortality. 
After the amputations, to be described in detail beyond, the 
best results were obtained by closing the wounds with a stitch 
or two of fine silk thread. Although this is not absolutely 
necessary to the success of the experiment, healing then takes 
place more rapidly and there is less danger of fungoid growths. 
Immediately after operation, the animals were placed in adark 
2 The experiment was made at the suggestion of Prof. T. H. Morgan, in 1907. 
