PHYSIOLOGY. 



7525 



few nerve cells occur a little earlier on the 

 chorda-tympani fibers, and a few a little later. 

 The sympathetic fibers which run through the 

 superior cervical ganglion are connected with 

 nerve cells in this ganglion, but at no other place 

 in their course from the spinal cord to their ulti- 

 mate endings. 



The objects of a comparative study of natu- 

 ral and artificial digestion by A. Sheridan Lea 

 were to obtain in artificial digestions some closer 

 approximation to the general conditions under 

 which natural digestion is carried on in the 

 body, and to apply the improved methods of 

 carrying on artificial digestion to the elucida- 

 tion of some special differences which so far 

 have appeared to exist between the natural and 

 artificial processes. An apparatus is described 

 by means of which digestions can be carried on 

 in a dialyzer in such a way as to provide for the 

 constant motion of the digesting mixture and 

 the removal of digested products. By this 

 method a partial reproduction is provided of 



I two of the most important factors in natural 

 digestion. Experiments upon the salivary di- 

 gestion of starch conducted under otherwise 

 similar conditions in the dialyzing digester and 

 a flask show that the rate of digestion in the 

 former is always greater than in a flask, while 

 the tendency to the development of bacteria is 

 greatly lessened ; that the amount of starch 

 converted into sugar is always greater in the 

 dialyzer; and that the total sugar formed and 

 small residue (4'29 per cent.) of sugar left dur- 

 ing an active and prolonged digestion in the 

 dialyzer justify the assumption that, under the 

 more favorable conditions existing in the body, 

 the whole of the starch is converted into sugar 

 before absorption. These results afford an ex- 

 planation of the existing discordant statements 

 as to the nature and amount of products formed 

 during starch digestion. Experiments upon the 

 tryptic digestion of proteids dealt chiefly with 

 the formation of leucin and tyrosin, and were 

 undertaken, initially, in order to find out why 

 those crystalline products are formed in large 

 amount during an artificial digestion, while they 

 have so far been described as occurring in mere 

 traces during natural digestion. The results of 

 the experiments made it probable that leucin 

 and tyrosin should be formed during natural 

 digestion. Examination of the contents of the 

 small intestine during proteid digestion showed 

 that, contrary to existing statements, leucin and 

 tyrosin are formed in not inconsiderable quanti- 

 ties during the natural process. The last part 

 of Mr. Lea's communication deals with the prob- 

 able physiological importance of the formation 

 of amidated bodies during tryptic digestion, and 

 a view is put forward as to the possible and 

 probable importance of amides in the chemical 

 cycle of animal metabolism. 



The studies of D. Noel Paton on the composi- 

 tion and flow of chyle were pursued with chyle 

 obtained directly from the thoracic duct of a 

 hospital patient afflicted with a sarcoma on the 

 posterior triangle of the neck. The average 

 rate of flow of milky fluid from the wound oc- 

 casioned by the operation was found to be 1 

 c. c. in one minute, or 1,584 c. c. in 24 hours. 

 The chief points of interest brought out by the 

 analysis of the composition of the fluid were : The 



small percentage of solids and their steady de- 

 crease during the course of the observation the 

 tolerable uniformity in the amount of the inor- 

 ganic substances; the small amount of the pro- 

 teids (the patient's blood pressure was very low) ; 

 the correspondingly small amount of cholesterin' 

 which is of interest as indicating that this sub- 

 stance has a source common with the pruiHil- 

 and the large proportion of fats, which is proba- 

 bly to be accounted for by the comparative rich- 

 ness of the patient's diet in those constituents. 



The fact that fats with a high melting point, 

 such as stearin, are not absorbed, is usually ad- 

 duced in support of the supposed importance of 

 em unification ; but some experiments described 

 by Dr. L. Munk show that a small amount (5 

 to 7 per cent.) of this fat may be absorbed. In 

 support of the saponification of fats the author 

 has described some experiments made on a pa- 

 tient with lymphatic fistula and on dogs. When 

 spermaceti was administered to the patient after 

 prolonged fasting the lymph became cloudy and 

 milky in the fourth hour of digestion. 'Analysis of 

 the whole lymph secreted during thirteen hours 

 showed that 15 per cent, of the spermaceti had 

 passed into the lymph, not, however, in an un- 

 changed condition, but as palmitin, showing 

 that the spermaceti must have been decomposed 

 in the alimentary canal, and that the palmitic 

 acid, of which it is partly composed, must have 

 become united with glycerin. Further experi- 

 ments with amyl alcohol verified the decomposi- 

 tion of this fat by producing symptoms of pois- 

 oning with amyl alcohol. The compound could 

 not, on account of its pungent taste, be given in 

 large enough doses to the patient with lymphatic 

 fistula to be conclusive ; but an analysis of the 

 lymph secreted from the fourth to the twelfth 

 hours showed that it contained not the com- 

 pound of oleic acid and alcohol, but olein a 

 further proof of its decomposition before absorp- 

 tion. So many difficulties stand in the way of 

 the view that all fats are saponified before'ab- 

 sorption that the author considers the various 

 points in connection with fat absorption as still 

 undetermined. 



Some six or seven different proteids having 

 been described as existing in milk,, an investiga- 

 tion of the whole subject has been made by W. 

 D. Halliburton to test the accuracy of the desig- 

 nations. The principal points to which the au- 

 thor would direct attention in his results are : 

 The principal proteid in milk, called caseinogen, 

 is precipitable by certain neutral salts, or by 

 acetic acid, and may be most satisfactorily pre- 

 pared, free from impurities, by a combination of 

 these two methods ; the term casein should be 

 restricted to the curd formed from caseinogen 

 by the action of rennet. In the classification of 

 proteids casein should be grouped with other in- 

 soluble proteids like fibrin and gluten formed by 

 ferment activity from pre-existing more soluble 

 proteids; caseinogen should be classified in a 

 new group, made to include it and whey proteid. 

 These proteids are similar to the globulins, the 

 chief difference being that their solutions are not 

 coagulated by heat like those of -the globulins, 

 but are only made opalescent. This opalescence, 

 if the heating has not been continued too long, 

 disappears on cooling. Lact-albumen is similar 

 in its properties to serum-albumen. It differs, 



