OCTOBEE 3, 1913] 



SCIENCE 



487 



We have defined the excess of water held by 

 tissues under various abnormal circumstances 

 and known under the varying names of exces- 

 sive turgor, plasmoptysis, edema, etc., as a 

 state of excessive hydration of the tissue col- 

 loids, more particularly of the proteins. As 

 the causes of this we have assigned any sub- 

 stance or condition which, under the circum- 

 stances surrounding the living cell, is capable 

 of increasing the hydration capacity of its 

 colloids. As the most potent of these causes 

 we have regarded, and still regard, an abnor- 

 mal production or accumulation of acid in 

 the involved cell. Of other substances con- 

 ceivably active in certain tissues, which thus 

 increase the hydration capacity of the tissue 

 colloids, we have studied urea. The addition 

 of urea increases in all concentrations the 

 swelling of gelatine and fibrin, and this the 

 more the higher the concentration of the urea. 

 In the higher concentrations of urea both gela- 

 tine and fibrin are hydrated so heavily that 

 they go into solution. The urea hydration is 

 not a simple alkali effect, for acid in no con- 

 centration counteracts it. The hydrating 

 effects of acid and of urea are additive. 

 There is, however, an interesting difference 

 between the increased hydration brought 

 about by acids and that induced by urea. 

 While salts reduce the former, they do not 

 affect the increased hydration induced through 

 urea. On the other hand, various non-elec- 

 trolytes which affect the hydration brought 

 about by acids but little, reduce that produced 

 by urea almost entirely. 



These facts, taken in conjunction with our 

 previous studies on the colloid-chemistry of 

 absorption and secretion, help toward an in- 

 terpretation of certain well-known biological 

 and medical facts. They explain on a colloid- 

 chemical basis the behavior of the sugars and 

 certain other organic substances in reducing 

 the absorption of water by tissues. They ex- 

 plain the cathartic action of glycerine, the 

 sugars, etc. They also explain the diuretic 

 action of these substances, accounting for the 

 polyuria of diabetes, the relative dryness of 

 the diabetic's tissues and his thirst. We get 

 an insight into the mechanism of urea hem- 



olysis. Also we learn another method of 

 dehydrating edematous tissues, which owe 

 their excessive hydration to other circum- 

 stances than the presence of acid or the ab- 

 sence of salts. In addition to using sugar in 

 order to correct the " acidosis " of certain 

 pathological states from a biochemical point 

 of view, we have made practical use of the 

 above facts by using sugar along with the 

 alkali and hypertonic salt mixtures previously 

 recommended in combating the edemas of the 

 eye (glaucoma), brain (uremia), medulla 

 (pernicious vomiting), kidney (nephritis), and 

 other organs observed in various clinical con- 

 ditions. The use of dextrose along with salts 

 and alkali in these conditions has yielded even 

 better results than have previously been re- 

 ported. 



A series of papers submitted for publication 

 in the Kolloid Zeitschrift will shortly bring 

 the details of these various findings. 



Martin H. Fischer 

 Anne Sykes 



ElCHBEEG LABOEATOET OF PHYSIOLOGY, 



■University of Cincinnati 



changes during quiescent stages in the 

 metamorphosis op termites 



There have been several theories as to when 

 the larvae of termites become differentiated to 

 the various castes in the social organization, 

 the prevalent theory being that undifferen- 

 tiated larvse are developed to the castes by the 

 character of the food that they receive. The 

 results of Heath's' experiments, however, to 

 determine the relation of various kinds of food 

 to polymorphism were negative. In case of 

 the ants, Wheeler' with Emery believes "the 

 adult characters to be represented in the germ 

 as dynamical potencies or tensions rather than 

 morphological or chemical determinants " and 

 that " nourishment, temperature and other en- 

 vironmental factors merely furnish the condi- 



> Heath, H., "The Habits of Calif oinia Ter- 

 mites," Biol. Bull., Woods Hole, Vol. IV., De- 

 cember, 1902, pp. 47-63. 



^^ Wheeler, W. M., "The Polymorphism of 

 Ants," Bull. Amer. Mus. Nat. Bist., Vol. XXIII., 

 January, 1907, pp. 1-93. 



