658 DIABETES 



50 grams and ])('i-liaps loss. Larger doses do not further increase the 

 rate of absorption. This rate may be 1.8 gram per kilo per hour. If 

 with this rate of absorption the rate of utilization in the bowel wall 

 and liver is 0.9 gram per kilo per hour, or less, glucose will enter the 

 systemic blood at the rate of 0.9 gm. per kilo per hour, or more, and 

 this will normally cause glycosuria. The physiological state of the 

 liver and the rate of sugar absorption are factors of chief importance 

 in determining alimentary glycosuria. Glycosuria following the in- 

 gestion of starch alone — alimentary gljjcosuria ex dmylo is said not to 

 occur in healtliy individuals. 



(2) Glycosurias which depend upon the discharge of sugar from 

 stored glycogen. These may be due to the action of (a) nerves, (b) 

 drugs, (c) the so-called internal secretions. 



(a) Claude Bernard's piqure, or puncture of the floor of the 

 fourth ventricle between the points of origin of the eighth and tenth 

 pairs of nerves, causes a glycosuria which ceases when the glycogen 

 of the liver is reduced to a low percentage. Following this operation 

 the l)lood is found to contain an excess of sugar (hyperglycemia") to 

 which the glycosuria is immediately due. If the vagus nerve is cut 

 stimidation of the central end has a similar effect, so that the vagus 

 is said to carry the afferent impulse to the center in the calamus 

 scriptorius. By severing different portions of the nervous system 

 and stimulating the cut surfaces, the path of the efferent impulse has 

 been traced from the glj^cogenic center through the cord to the upper 

 thoracic spinal roots, by the rami commimicantes to the inferior cer- 

 vical and superior thoracic ganglion, thence via the splanchnic nerves 

 to the liver. This center and nervous arc form probably an im- 

 portant link in the mechanism for regulating the quantity of sugar 

 in the blood. Nervous glycosurias having the same mechanism as 

 "la piqure" occur in a great variety of conditions associated with 

 insult to the nervous system, e. g., commotio cerebri, brain tumor, 

 tabes, meningitis, severe mental shock, etc. How a splanchnic impulse 

 operates to cause increased hydrolysis of glycogen is unsettled. Gly- 

 cogen hydrolyzes outside the body under the influence of acids, /". e., 

 of n ions or plus charges of electricity, and a nerve impulse might 

 tlieoretically operate directly, or, as McLood has suggested, through 

 an increase of glycogenase in the liver; or as held by the von Noorden 

 school, by causing an increased secretion of einnephrine — since ]ii(|ure 

 glycosuria is said not to occnr in animals deprived of the adrenals 

 '^ flayer, Kahn, Nishi) or after section of tlie left splanchnic nerve, 

 which supi)lies both adrenals, (b) Similar phenomena occur in as- 

 ])hy.\ia (carbonic and lactic acid accumulation), and when acids are 

 directly administered; also alter the administration of certain drugs 

 whose effects, including lactic and carbonic acid accumulation in the 

 l)ody fluids, closely ])aT-allel those of a deficient oxygen suj^jily (phos- 

 pliofiis, carbon monoxide, chlorofoT-m, iiNdi-azinc, arsenic, etc.). 



