ix MID- AND INTEE-BEAIN 515 



tractions of the stomach, intestine, and bladder. Hlasko stated 

 more definitely that there is a centre in the posterior corpora 

 quadrigemina for the contraction of the stomach which induces 

 vomiting. When these bodies are destroyed vomiting is no longer 

 produced by apomorphine. Frequently repeated vomiting may 

 occur in dogs in which the quadrigeminal bodies have been 

 partially injured, and therefore irritated, during extirpation of the 

 anterior vermis of the cerebellum. After three or four days the 

 vomiting ceases, probably owing to the cessation of the irritation. 



VIII. The anatomical relations of the optic tracts with the 

 optic lobes and anterior corpora quadrigeniina show that these 

 ganglia are of supreme importance in vision. But the clearest 

 and most unmistakable demonstration of the different centres 

 that are in direct relation with the optic nerves, and therefore 

 function in vision, is given after extirpation of one eyeball in 

 young animals and in man ; this produces atrophy and partial 

 agenesis of the anterior quadrigeminal body and the external 

 geniculate body on the opposite side, as well as of the optic 

 thalamus and cortex of the occipital lobe, while the posterior 

 quadrigemiual body and internal geniculate body are spared. 

 Evidence for this is shown by the experiments and clinical 

 observations of Pauizza, Svan, Gudden, Ganser, Forel, and v. 

 Monakow. 



Mayer, Flourens, and Budge, experimenting on pigeons and 

 dogs, first pointed out that the destruction of the optic lobes and 

 corpora quadrigemina produced loss of vision and immobility of 

 the, pupils. They noticed that these effects are crossed, that is, 

 unilateral destruction produces paralytic effects on the retina 

 and iris of the eye on the opposite side. Longet, Eenzi, Stefani, 

 and Miiuzer and Wiener confirmed these observations ; but found 

 that the blindness consequent on destruction of the optic lobes 

 was not complete. Lussana and Lemoigne stated that total blind- 

 ness, at least for a few days after the operation, occurred only 

 after destruction of the anterior corpora quadrigemina, and that 

 amblyopia only resulted from destruction of the posterior quadri- 

 geminal bodies. They further held that paralysis of the pupil 

 ensued only when these parts were seriously injured. Many 

 observers found that unilateral ablation of the quadrigemiual 

 bodies produced circus movements, but they do not agree as to 

 whether such movements were towards the healthy or the operated 

 side. Ataxia and disorders of equilibrium were further observed 

 after destruction of the quadrigeminal bodies, but they are not 

 unilateral and do not persist; probably they depend on injury 

 of the adjacent or subjacent parts. The same holds good for 

 functional disturbances of the internal ocular muscles, which 

 possibly depend on injury of the nucleus of origin of the oculo- 

 motor nerve. 



