672 A. F. Goldfarb 
Destruction of Less than 5 mm. of the Nerve Cord 
The operation was the same as that previously described. The 
cord was removed from 2 to 44 mm., by a needle, or glass capillary 
or, better still, by the broach. In nearly every instance—where 
sufhcient time was allowed—a new tail regenerated. It was 
somewhat slower in making its appearance than in the control 
animals, but, having once appeared, further growth was quite 
normal. Here too it is very probable that the injury to bones and 
surrounding muscles, rather than any direct effect of the lack of 
nerve supply, is responsible for this retardation. It was pointed 
out In a preceding section that under certain conditions disinte- 
gration of the wounded end often took place. This possibility 
was kept in mind and unless specifically mentioned to the con- 
trary all tail stumps measured at the time of fixation exactly the 
same as after the operation. There sometimes appeared a dis- 
crepancy of 4 to ? mm., but this was probably due to the contrac- 
tion of the tissues at the wounded end.5 
The following six animals however showed no external sign of 
regeneration, though 30 to gi days had elapsed after the operation. 
No. 1.1 B. The tail was amputated close to its base, then 
4 mm. of the cord was destroyed with the needle. After 30 days 
no regeneration had occurred. 
Between 5 and 4 mm. from the end, the cord was normal in size 
and shape. ‘The fibrous layer however had degenerated and disin- 
tegrated, giving to the cord a very vacuolated appearance, one-half 
of which is shown in Fig. 5. The cellular or neuroglia layer has 
been greatly decreased, due to the degeneration of many of the 
cells. Just posterior to this level the cord suddenly shrinks to 
about one-half its normal diameter, and becomes very misshapen. 
The dwindling proceeds to within 2 mm. from the amputated 
surface, at which place the cord ends as an irregular clump of 
degenerate cells. Without going into further detail, it may be 
said that there is every evidence that the needle has merely injured 
the cord between the 4th and the 2d mm., while between the 
5 All measurements are made anterior or posterior to the amputated level. 
