REMARKS ON REGENERATION 841 
observed that the injured Pycnogonides continue to molt. 
Texpect to resume these experiments and to fill out the gaps 
left in this study. 
Il. ON THE THEORY OF REGENERATION 
1. Systematists have found it difficult to place the Panto- 
pods in the natural system upon the basis of their morpho- 
logical and developmental characteristics. It might be 
thought that under such conditions the consideration of the 
physiological behavior of the animals might offer advantages. 
On the basis of our observations on the regeneration of 
Pantopods it might appear as if the Pantopods were closely 
related to the Annelids; but this conclusion would be inac- 
curate, for, as is well known, a whole group of Annelids, the 
leeches, do not regenerate body segments which have been 
lost, even though transverse pieces cut from the leech may 
remain alive for more than a year. One would therefore 
have to reason that the Pantopods are more closely related 
to the Chetopods than the Hirudinee, which would be 
absurd. 
2. One frequently encounters the statement that the 
capacity for regeneration in animals decreases the higher 
animals stand in the natural system. This idea has been 
stated in a very definite form by Nussbaum: “The capacity 
of regeneration of organisms is proportional to their sys- 
tematic position, as determined by their characteristics, and 
decreases from below upward.’ This generalization goes 
too far, as can be seen from the facts mentioned above. 
Usually we find in every large group in the animal kingdom 
certain species with a greater, and others with a smaller 
power of regeneration. The salamander regenerates an 
amputated tail, inclusive of the spinal column and spinal 
cord, and this power of regeneration is almost as great as 
1NussBaum, Sitzungsberichte der Niederrheinischen Gesellschaft fir Natur-u. 
Heilkunde, Bonn, November 5, 1894. 
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