REFLEX ACTION OF THE SPINAL CORD. 813 



noted by Gluge 1 in the spinal rabbit, later by Goltz 2 in the dog. The 

 skeletal musculature atrophies utterly, and comes to resemble connective 

 tissue. The bones get brittle. Visible perspiration cannot — as far as 

 noted in the dog — be induced. 



These details serve to indicate the status obtaining in dogs preserved 

 for even year-long periods after spinal exsection. The status is not, how- 

 ever, established forthwith. For a variable but not very prolonged period 

 the ablation depresses the vascular function and tonus of the sphincters. 

 These gradually recover. Congestion and oedema of the feet, diarrhceic 

 stools, retentio urince, patulous gaping of anal and vaginal ostia, 

 are symptoms which in the course of some weeks subside. But 

 the wasting of the striate musculature, save in these sphincters, 

 is progressive and complete. If the spinal ablation involve the 

 thoracic region, the tissue normally thick with muscle in the inter- 

 costal spaces becomes transparent and " as thin as paper." In the eel, 

 when a length of the cord midway between head and tail has been 

 destroyed, the musculature is permanently slack, although there is good 

 co-ordination between the movements of the front and hind end of 

 the animal in swimming. 3 So in Lumbricus the ablation of a single 

 abdominal ganglion leaves the local musculature permanently slack. 4 



These changes can be averted in any particular region by retention 

 in that region of even a short fraction of the length of the spinal cord. 

 And in addition, as discovered by Whytt, the solidarity of the whole 

 cord is not necessary for the exhibition of local reflex reactions. When 

 Amyhioxus 5 is separated by a couple of transections, each of the three 

 pieces balances itself in water, and executes swimming movements that 

 appear co-ordinate and result in an apparently — so far as the fragment 

 represents the whole — normal locomotion, always with the head-end of 

 the fragment foremost. Of the three pieces, that possessing " the head " 

 exhibits movement spontaneously ; but the two other pieces, although 

 progressing co-ordinately under stimuli and maintaining normal posture, 

 exhibit little spontaneity. The severed tail-fragment of Triton moves in 

 response to contact. Keflex movements persist in the hind-limb of Rana 

 when the piece between the sixth and eighth nerves is the only portion of 

 cord undestroyed. Alternating side-to-side movements have been evoked 

 from the tail of the monkey after spinal transection at the level of the 

 penultimate sacral nerve root. These phenomena are comparable with 

 the reflex attachment of the suckers provocable from even an amputated 

 arm of Octopus on its contact with a solid object. 6 



In the frog, after spinal transection close below the brachial region, 

 the reflex movements of the hind-limbs are distinctly co-ordinate. 

 If a pedal digit be pressed, the limb is drawn up. The following is a 

 usual sequence of events. First the dorsal flexors of the toes and 

 tarsus act, then follows somewhat slow flexion at knee, then fairly 

 synchronous contraction of the flexors of the hip and tarsus, so that the 

 calf is deliberately placed against the thigh, the thigh in contact with 

 the abdomen. Frequently the intact frog, in response to a similar 

 stimulus, executes a movement to all appearance similar. Some groups 



1 Bull. Acad. roy. dc mid. de Belq., Bruxelles. 1868. 

 2 Arch.f.d. ges. Physiol., Bonn,'l873, Bd. vii. S. 582. 



3 Bickel, ibid., 1897, Bd. lxviii. S. 110. 



4 Maxwell, ibid., 1897, Bd. lxvii. ; Chicago Lah. Rep. of J. Loeh, 1898. 



5 Dnnilewski, Arch. f. d. ges. Physiol., Bonn, 1892, Bd. Hi. 



6 W. B. Carpenter, "Principles of Physiology," 3rd edition, London, 1851. 



