178 Report S.A.A. Advancement of Science. 



components of the blood (Hess), and accumulation of CO., causes an 

 increase in concenti'ation of albumen, sugar and fat (Hamburger). 



The internal friction of urine is chiefly dependent on the concen- 

 tration of its salts ; other substances are put out with the urine only in 

 pathological cases (albumen, sugar, bile pigments, haemoglobin) ; these 

 all increase the viscosity. The majority of the salts inci-ease the 

 viscosity of water, for instance, NaCl, which is the most prevalent, 

 then phosphates, sulphates and urea ; KCl only decreases it. A 

 sudden alteration of the viscosity indicates the variation of the salt 

 concentration or the appearance of the above-mentioned colloids in the 

 urine (piroplasmosis). 



(b) Surface Tension. 



Surface tension or surface pressure is a force which acts on the 

 surface of any substance, solid or liquid, having the tendency to make 

 it as small as possible, therefore causing the globular form of a drop of 

 liquid. The same force is the cause of capillary attraction and capillary 

 depression, because it is less on a concave, and greater (jn a convex 

 meniscus than on a plane surface. A great number of salts (chlorides 

 of Li, Na. K, NH„ Ba, Sr, Ca, Mg ; sulphates of Na, K, Mg, Mn; 

 and nitrates of K and Na increase the surface tension of water 

 (Whatmough). Colloids, however, have a decreasing influence, because 

 their particles are condensed in the surface (Gibbs). The surface ten- 

 sion of colloids is also changed by the various kations and anions, as I 

 have stated, and it is especially the OH ion which has a very pro- 

 nounced and characteristic effect. My preliminary experiments permit 

 of the deduction that the surface tension of serum and other liquids of 

 organisms is the balance of the eflects of the concentration of the 

 colloidal components and the different ions and non-electrolvtes. As a 

 matter of fact it is lower than the surface tension of water, whilst, as 

 mentioned, the viscosity is higher. The effect of the colloids and other 

 decreasing substances is of course prevalent. 



The alkalinity of serum gives the value of surface tension a certain 

 height and perhaps stabilit3^ I have observed that neutralisation 

 caused a considerable decrease of the surface tension. In all proba- 

 bility the influence of the degree of alkalinity of the serum or plasma 

 on phagocytosis (Hamburger and Hekma*) is to a great extent depend- 

 ent on the surface tension of them, which is influt^nced by their 

 alkalinity. 



Investigations on the serum of horses, mules, cattle, sheep and 

 goats lead to the cijiiclusion that a certain value of surface tejision is 

 ;haracteristic for the serum of each species. 



Series of experiments on horses have proved that during an 

 attack of piroplasmosis or horse-sickness the surface tension of serum 



■ Plia<;(K'.yt<)«is is at a iiiaxiiiunii at an oi)tiiiial fonceiitiatidii of OH ions 

 ()iot in'oportioual) wliicli is just i)reseiit in tlie serum. 1 also f<jnnil an t>ptinial 

 concentration of OH for a inaxinial surface tension of jiclatin ainl serum. 



