812 EEPORT— 1894. 



5. On the Production of Heat in Hibernating Animals. 

 By Raphael Dubois, Professor of Physiology in the University of Lyons. 



For several years the author has investigated the production of heat in the 

 marmot in order to find out what part of the nervous system is essential for the 

 rapid production of 'heat which takes place when the animal wakes up from its 

 ■winter sleep. 



Section of the spinal cord at the level of the fourth cervical vertebra prevents 

 the animal from raising its temperature. Destruction of the grey substance of the 

 train produces a similar efi'eet. If the section of the spinal cord be made at the 

 level of the seventh cervical vertebra the animal grows warm slowly and incom- 

 pletely ; but if the operation be performed between the fourth and iiftti dorsal 

 vertebrje, then the curve of the rise of temperature presents the normal form. 

 There is therefore a limited portion of the cord, between the fourth cervical and 

 the first dorsal vertebrae, through wdiich pass the centripetal or centrifugal, or both, 

 impulses, placing the cortex of the cerebral hemispheres in communication with the 

 rest of the organism. The pathway is through the grey substance of the spinal 

 cord, for section of the autero-lateral or of the posterior columns does not prevent 

 the animal from producing heat, whereas destruction of the grey matter in this 

 limited portion of the cord produces the same eil'ect as total section. This opera- 

 tion produces immediate loss of the power of movement and conscious sensibility 

 in the greater part of the body ; but tlie absence of the capacity to produce heat 

 must not be attributed to this sensory and motor paralysis, for section a little 

 lower, at the fourth dorsal vertebra, does not change the normal curve of tempera- 

 ture. 



The section of the cord at the fourth cervical vertebra abolishes, on the one 

 hand, the contractions of the thoracic muscles, the activity of which is very great 

 during the rewarming and insignificant during the torpor; on the other hand, it 

 cuts oft' the very important connections of the sympathetic system with the higher 

 centres. If the cervical sympathetic be cut on both sides above the inferior 

 cervical ganglion there is no very marked delay in the production of heat, whereas 

 the rise of temperature is very slow and incomplete when the inferior cervical and 

 the first thoi'acic eanglia are removed on both sides. These ganglia, however, are 

 only connecting links, for the same result is obtained by section of the two 

 splanchnic nerves or of the branches which pass directly from the abdominal 

 sympathetics to the semikuiar ganglia. Extirpation of the semilunar ganglia 

 produces the same result as removal of the inferior cervical and first thoracic 

 ganglia. 



Experiments show that it is by acting upon the portal system that the sympa- 

 thetic shares in the general process of heat production. It regulates the quantity 

 nnd pressure of the blood which flows to the liver, and in this manner the produc- 

 tion of heat in the liver and the transformation of glycogen into sugar, to be 

 utilised for combustion when the animal awakes. The thoracic muscles become 

 exceedingly active when the animal awakes, and thus require more glycogen or 

 other combustible material for their contraction. 



A full account of this research will shortly be published in ' Les Annales de 

 i'Universite de Lyon.' 



6. On ^Pigeons' Milk.' By E. Waymouth Reid, Professor of Physiology 

 in University College, Dundee. 



John Hunter (1786) discovered the fact that pigeons feed their young for some 

 ■days after hatching upon a substance resembling the curd of milk, and formed in 

 the lateral pouches of the crop of both cock and hen. This method of feeding is 

 AS yet only known in this tribe of birds. 



Claude Bernard (1859) studied the nature of the substance, and found that 



