OTHER VISCERAL REFLEXES. 853 



If through the skin more posteriorly the glans penis be pressed, the posterior 

 end of the body is curved downwards, pushing the penal bone forward. 

 These reflex movements suggest themselves as belonging to the act of 

 copulation, and this suggestion is strengthened by failure to obtain similar 

 movement on touching the analogous parts of the spinal bitch. 



At breeding-time the male frog covering the female clasps her with his 

 fore-limbs during four to ten days so vigorously, that much force is required to 

 separate him from her. Decapitation of the male does not, as a rule, suffice to 

 do so. The sexual posture is maintained as a spinal reflex. 1 The 

 cord may be divided both in front and behind the brachial region 

 without interrupting the reflex. Experiment shows that from the 

 spinal male frog at the breeding-season, and also at other times, the 

 reflex is elicited by any object that stimulates the skin of the sternal 

 and adjacent region. In the intact animal, on the contrary, other objects than 

 the female are, when applied to that region, at once rejected, 2 even although 

 they be wrapped in the fresh skin of the female frog, and in other ways made 

 to resemble the female. The development of the reflex is not prevented by 

 removal of the testes, but removal of the seminal reservoirs is said to depress it, 

 and their distension, even by indifferent fluids, to exalt it. If the skin of the 

 sternal region and arms is removed, the reflex does not occur. Severe muti- 

 lations of the limbs and internal organs does not inhibit the reflex, neither 

 does stimulation of the sciatic nerve central to its section. The reflex is, 

 however, depressed or extinguished by strong chemical and pathic stimuli to 

 the sternal skin, at least in many cases. The tortoise exhibits a similar sexual 

 reflex of great spinal potency, and Tarchanoff 3 and Albertoni 4 discovered 

 simultaneously that even weak excitation of the optic lobes (mesencephalon) 

 immediately inhibits the reflex in both frog and tortoise ; without exciting 

 contraction in other muscles, those exciting the sexual clasp are at once relaxed, 

 and the male drops from the female. Stimuli applied to the optic thalami 

 occasionally produce the same effect, but other parts of the brain and cord fail 

 to give the reaction. 



Other visceral reflexes. — As regards other viscera than the above, 

 little concerning their relations with the spinal cord remains to be said, further 

 than that already stated actually or by implication in the chapters on 

 digestion, renal action, vasomotor distribution, and on the sympathetic nervous 

 system. A frequent and troublesome sequel to high spinal transection, e.g. in 

 the brachial region, in the dog, is an alteration in the character of the fasces, 

 these becoming fluid, frequent, copious, and laden with mucus. The explanation 

 lies, perhaps, in vasomotor disturbance having caused congestion of the 

 intestines. The same result follows exsection of pieces of the thoracic region 

 of the cord. Brachial transection (i.e. above brachial roots and below phrenic) 

 in the rabbit immediately gives rise to obvious increase of peristaltic activity 

 in the intestines. 5 This does not follow a bulbar transection in front of 

 the vagus root. Whether the cord gives secretory nerves to the intestines, 

 has been discussed in another part of this work. 6 In frogs the secretion 

 of urine is said to continue normally after the whole spinal cord has been 

 destroyed. 7 In the dog, inasmuch as the flow of urine is abolished when the 

 aortic pressure falls to 40 mm. Hg, and as it has been frequently noted to fall 



1 Spallanzani, " Opera sopra la riproduzioni animali," Modena, 1768 ; " Exper. sop. la 

 generaz. dei animali e veget.," 1785. 



2 Goltz, Cmtralbl. f. d. med. Wissmsch., Berlin, 1865, No. 19; 1866, No. 18. This 

 statement will not apply, however, to the male toad. 



3 Arch. f. d. ges. Physiol., Bonn, 1887, Bd. xl. S. 340. 



4 "Man. di tisolog. d. homo," Milano, 1887 ; Arch. ital. de biol., Turin, 1887, pt. 1. 



5 C. Bernard, " Lecons sur le systeme nerveux," Paris, 1858, tome i. p. 378. 



6 J. S. Edkins, "Mechanism of Secretion of Intestinal Juice," this Text-Book, vol. i. 

 p. 555. 



7 Bidder, Arch. f. Anat., Physiol, u. wissmsch. Med., Berlin, 1844, S. 347. 



