Effect of Successive Removal upon Regeneration 507 
(97) finds in Tubularia that the character of the regenerated part, 
polyp or root-stock, is changed from one to the other with succes- 
sive removal. 
Conclusions Regarding Data from the Literature 
In general the facts are not reliable (first) because of the vague 
and general manner in which the statements are made implying 
merely an astonishment because the successive removal showed 
regeneration at all, and (second) because the additional factors 
likely to control the result such as age, temperature, etc., are not 
considered. The general concensus of opinion seems, though 
with a great deal of hesitation, to favor the view that successive 
removals followed by regeneration do not change the rate or other 
characteristics of the regeneration. The most striking exception 
is that of Vanlair (’94), who finds a distinct advantage in favor of 
the second regeneration of the sciatic nerve of the dog as compared 
with the first. 
V GENERAL-STATEMENT OF THE FACTS AS OBTAINED FROM ALL 
SOURCES 
The determination of the effect of successive removal upon the 
rate of regeneration is not a simple matter. Before proceeding 
further, it is necessary to emphasize a few points that have an 
important bearing on the interpretation of the data. 
1 Special emphasis should be placed on the fact that every dis- 
turbing condition affecting the physiological state of an animal is a 
factor causing decrease in rate with successive removal. Hence, 
a result showing an increase or no change in rate must have an 
additional weight from this fact alone. At least nothing is more 
certain than that poor physiological condition, even if present in 
small degree and affecting both series of animals alike, must yield 
a result giving decrease in rate. 
2 A factor whose effect is in part at least constitutional cannot 
be expected to have either uniformity or considerable magnitude. 
3. Inthe determination of a factor whose value is less than that 
of a considerable number of other factors all of which are operating 
