PARALYSES IN DOGS 105 
(including employment of other paths in the cord); (3), failure 
of many of the neurones originally pressed on by the exudate to 
degenerate completely, so that with removal of the exudate they 
recovered their functions; (4), changes in subjective state in the 
animal as brought about by lessened discomfort. (The last two 
explanations might also apply to the early improvement.) We 
cannot say which of these factors were most important—in fact, 
it is possible that all of them had a share in explaining the clin- 
ical change for the better. 
Previous researches on the subject 
That marked restoration of power may occur after lesions in 
the central nervous system is well known. This applies both 
to cortical extirpations,? and to hemisections in the cord.* The 
fact that there is also considerable restoration of power after 
complete section would seem to indicate that there might be 
regeneration across the scar. This has been actually observed 
in some of the lower animals.4. Brown-Sequard noted it in fishes 
and Fraisse in amphibians. But in higher animals it has not been 
observed,* and for this reason, in cases of hemisection restoration 
of the clinical state has been said to be partially due to the em- 
ployment of paths on the contralateral side. Be that as it may, 
it is not necessary to base the restoration of function on nerve 
repair across the scar because the clinical improvement seemed 
practically as great in our cases where, on account of the extent 
of the lesion, conditions for nerve repair were not favorable and 
where, moreover, signs of such repair were scarcely to be made out. 
Bearing of above inferences on infantile paralysis 
The spontaneous restoration of power noted in our dogs is 
very similar to that often observed in infantile paralysis. This 
applies both to the early and late improvement. The former, 
2 Sherrington: Integrative action of the nervous system, 1906, p. 277. 
3 Weiss: Sitz. d. Akad. d. k., Wissensch., Wien, 1879, Bd. 80. 
¢ Bechterew: Functionen der Nerven Centra, 1908, vol. 1, p. 652. 
5 Schiefferdecker: Virchow’s Archiv, Bd. 67. 
