i 2 6 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



the place of operation a change which is sometimes 

 transitory, sometimes permanent the so-called shock- 

 effects. The highest degree of these shock-effects is 

 attained in case of degeneration. It is a remarkable 

 fact that, in an operation on the central nervous sys- 

 tem, the effect of the shock is much greater in the 

 part posterior to the place of operation than in the 

 anterior part, toward the head. This may indicate 

 that there is a constant current of impulses or influ- 

 ences in the direction from the brain to the posterior 

 parts of the central nervous system. The interrup- 

 tion of these influences may be responsible for the 

 condition which we call shock-effects and which may 

 be transitory. These shock-effects are incomparably 

 less stronor in cold-blooded than in warm-blooded ani- 



^> 



mals. We do not possess enough facts to enable us 

 to give an explanation of the shock-effects. 



BIBLIOGRAPHY. 



1. HYDE, IDA H. The Nervous Mechanism of the Respiratory 

 Movements of Limulus Polyphemus. Journal of Morphology, vol. 

 ix., 1894. 



2. LANGENDORFF, O. Studien iiber die Innervation der Athembe- 

 wegungen. I. Mittheilung. Archiv f. Physiologie, 1880. 



3. PORTER, W. T. The Path of the Respiratory Impulse from 

 the Bulb to the Phrenic Nuclei. Journal of Physiology, vol. xvii., 

 1894-95. 



4. VULPIAN. Lemons sur la Physiologie generate et compare'e du 

 Systeme Nerveux. Paris, 1866. 



5. BETHE, A. Vergleichende Untersuchungen iiber die Functionen 

 des Centralnervemy stems der Arthropoden. Pfliiger s Archiv, Bd. 

 Ixviii., 1897. 



