164 REPORT — 1866. 



nution of muscular irritability. But this wiU not account for the paralysis 

 for we have many examples in which frogs would move their limbs by voli- 

 tional effort, where the m uscles are far less irritable, and rapidly passing into 

 a rigid state ; such examples are furnished by certain stages of thermal 

 tetanus. The following experiment wiU throw light upon the real causes of 

 the paralysis. 



August 10, 4 P.M. Compression was exercised upon the abdominal aorta 

 of a frog. It was then ascertained by the microscope that the cii'culation in 

 the limbs was completely arrested. The sciatic nerve of one limb was then 

 divided. The paralysis of this Umb was complete. The creature had per- 

 fect control over the limb deprived of blood, hut with the nerve intact. In 

 about an hour afterwards it was observed tliat, although quite vigorous, it 

 had lost all control over this limb. I tested the muscles of both limbs for 

 irritability, and found them in both cases tolerably sensitive. The distal 

 extremity of the cut nerve is also ii-ritable. 10 p.m. The limb possessing 

 its nerve remains perfectly paralyzed, and is, with the other limb, dragged 

 after the frog at fuU length. The tourniquet was now removed from the 

 aorta, and the creature placed in water. At this time the muscular irrita- 

 bility was at a very low ebb. At 8 a.m. Aug. 11, the frog was much in 

 the same condition ; the limb in possession of its nerve and artery was still 

 completely paralyzed, although the muscles of both limbs had acquired in- 

 creased susceptibility to galvanism. On examining the webs, I fomid a free 

 circulation now going on in both limbs. The sensation in the skin of the 

 paralyzed limb possessing the nerve is perfect. 1 p.m. No return of motor 

 power in the anatomically perfect Umb. 9 a.m. Aug. 12. The limb is stiU 

 paralyzed, but the muscles are very irritable, in fact, more than normallij so. 

 At 8 a.m. Aug. 13, the firog was placed under the influence of strychnia, to 

 ascertain if the nervous impulses generated by the drug would pass over the 

 nervous obstruction and contract the highly irritable muscles. Not the 

 slightest effect, however, was produced. 



This experiment shows that in thus ciitting off blood from a limb we in- 

 terfere seriously with the functions of the motor nerve ; and as in animals 

 deprived of blood the excitability of nerve-tissue is always first to perish, it 

 is legitimate to assume that this degradation of the nerve is the primary 

 effect of cutting off the blood from a limb, and therefore the cause of the 

 paralysis. This functional degradation of the nerve being brought about 

 immediately in warm-bloods and gradually in cold bloods, is consistent "with 

 aU our knowledge of the differing degrees of vital persistence possessed by 

 these classes respectively. This experiment further proves that the nerve 

 may sufter past restoration by prolonged absence of blood, but that the mus- 

 cular irritability may be completely restored — in fact, exalted. 



The question as to the part of the motor neive (tlie trunk or the terminal 

 branches) concerned in the paralysis is one of extreme interest. Inasmuch 

 as the sensory fibres still convey their impressions, it seems probable that the 

 defect in the nerve must lie in its ultimate distributions to the muscular 

 tissue ; otherwise we should have to consider that the motor fibres of the 

 trunk of a nerve are dependent upon the general circulation of a limb for 

 their integrity, and that the nutrition of the sensory fibres of the same trunk 

 is maintained in some other way. There seems to be a remarkably interesting 

 analogy between this form of paralysis and that induced by the action of the 

 woorara poison*. 



* How is it that the terminations of the motor nerves in muscles are so interfered with, 

 wliile neither the trunk or its ramifications, nor the muscular tissue, appears to be affected 



