vii THE MEDULLA OBLONGATA 415 



recently Steiner, that after excision of the whole of the brain, 

 except the bulb, fish can swim and maintain their normal position 

 with the back uppermost. The decerebrated frog, according to 

 the well-known experiments of Goltz, remains motionless in the 

 normal position ; it responds by a series of regular springs to 

 slight stimuli, and if thrown on to its back turns over again to 

 recover its normal position. Toads differ from frogs only in the 

 fact that after decerebration they creep about periodically like 

 land tortoises. The latter, according to Fano, also try to resume 

 the normal position when placed on their backs ; after remaining 

 motionless for some time the animal extends its neck, makes a 

 lever of its jaws against the ground, and agitates its limbs so 

 forcibly as to rotate its body on the long axis, which brings it 

 back to the normal position. Not invariably, but in most cases, 

 these repeated efforts attain their object : sometimes the decerebrate 

 tortoise turns over almost as quickly as the normal animal. 

 Similar facts are observed in birds and mammals. Both pigeons 

 and young rabbits after removal of the brain as low as the pons 

 stand upright and walk if stirred up. Even without external 

 stimuli they move about periodically like tortoises, but as soon as 

 the pons is destroyed or injured, standing and walking become 

 impossible. 



The recent experiments of Baglioni (1909) have proved the 

 existence in the toad of true sensory centres in the dorsal region 

 of the upper third of the bulb, which preside over the movements 

 of the hind-limbs and possibly of the fore-limbs as well. He 

 isolated the cerebrospinal axis of the toad (Fig. 166) and found 

 that electrical and mechanical stimulation of this region not only 

 evoked movements of the limbs, but is capable, under the influence 

 of a local application of strychnine, of profoundly modifying the 

 reflex acts evoked from the hind-limbs by peripheral stimuli. 



Maguini and Bartolomei, who experimented under Baglioni's 

 guidance upon dogs, found that the local application of strychnine 

 to different parts of the dorsal surface of the bulb provoked various 

 effects, as hyperaesthesia and paraesthesia in the peripheral dis- 

 tribution of the cranial sensory nerves, particularly the fifth pair, 

 spontaneous muscular contractions, spasms of different muscles 

 of the face and neck, dyspnoea, vomiting, disturbances in gait, 

 erection of penis. Assuming that strychnine acts electively upon 

 the sensory central elements, these results are in favour of the 

 hypothesis that there are in the bulb, and particularly in its dorsal 

 part, centres which are mainly sensory. This conclusion agrees 

 with the other results obtained by these observers, viz. that local 

 application of weak solutions of carbolic acid which stimulates 

 motor elements (p. 264) produces hardly any effects. 



X. Are all these highly complex automatic actions and re- 

 flexes of which bulbo-spinal animals are capable accompanied by 



