SURFACE MEASUREMENTS 



236 



TANTALUM 



5 sq. meters — Policard, A., Precis 

 d'Histologie Physiologique. Collection 

 Testut, Paris: G. Doin, 923 pp., after 

 Potter. 



Large intestinal crypts — 4.2 meters — 

 Policard, ibid. 



Mitochondrial, zymogenic and nuclear 

 surfaces in pancreatic acinous cells of 

 guinea pig — duNouy, P. L. and Cowdry, 

 E. v., Anat. Rec, 1927, 34, 313-329. 



Respiratory surface plus nonrespira- 

 tory epithelial surface of airways of 

 lungs — 70 sq. meters — Wilson, H. G., 

 Am. J. Anat., 1922, 30, 267-295. 

 Surface Tension. This, or more correctly 

 interfacial tension, is tension at the 

 surface of a fluid tending to produce 

 a sphere. Surface tension is high for 

 water and low for alcohol. Soap de- 

 creases surface tension of water because 

 it concentrates at surfaces. Bile acids 

 lower surface tension of blood serum. 

 According to Gibbs any substance 

 lowering interfacial tension will con- 

 centrate at the interfaces. Surface 

 tension is best determined by a Cenco- 

 du Nouy tensiometer capable of meas- 

 uring the force required in lifting a 

 standard platinum ring out of the 

 surface of the liquid. The ring must 

 obviously be held absolutely horizontal 

 and be pulled away slowly (Holmes, 

 H. N., Glasser's Medical Physics, 257- 

 263). 



Much has been written about surface 

 tension (Reviews: Harvey, E. N., and 

 Danielli, J. F., Biol. Rev., 1938, 13, 

 319-341 and Danielli, J. F. in Bourne, 

 pp. 69-98). Before measurements can 

 be made on cells it is obviously neces- 

 sary to isolate them and this entails 

 risk of injury which is much greater 

 in the case of mammalian cells than of 

 the sea urchin eggs usually employed. 

 The following techniques are given as 

 examples : 



1. By centrifuging marine eggs elon- 

 gation can be produced and, when the 

 length exceeds a certain ratio of diam- 

 eter, the egg divides. Knowing the 

 minimum force required, the difference 

 in density between the 2 halves and the 

 circumference of the cylinder, it is 

 apparently possible to calculate the 

 tension at the surface (Harvey, E. N., 

 J. Franklin Inst., 1932, 214, 1-23). 



2. By compressing sea urchin eggs 

 by a minute gold beam the internal pres- 

 sure can be calculated and from this the 

 surface tension (Cole, K. S., J. Cell & 

 Comp. Physiol., 1932, 1, 1-9). 



3. By stretching a cell between the 

 two needles of a microdissection ap- 

 paratus the force required to secure a 

 given degree of elongation can be deter- 

 mined and thence the surface tension 



(Norris, C. H., J. Cell & Comp. Physiol., 

 1939,14, 117-133). 



4. Surface tension is probably to 

 some extent at least conditioned by the 

 elasticity of the superficial plasma gel 

 layer which brings in the methods and 

 observations of Lewis, W. H., Arch. f. 

 exp. Zellf ., 1939, 28, 1-7 ; Am. J. Cancer, 

 1939, 35, 408-415 who refers to previous 

 work along this line. 



Survival of Tissues after death of the body 

 (Alvarez, W. C, Quart. Rev. Biol., 

 1937, 12, 152-164). Often determined 

 by measuring how long the tissue con- 

 tinues to respire. Data for whole skin, 

 kidney and liver (Walter, E. M., Shar- 

 lit, H. and Amersbach, J. C, J. Invest. 

 Dermat., 1945, 6, 235-238). Schrek, R., 

 Radiology, 1946, 46, 395-410 has made 

 much use of a method for measuring the 

 survival of cells in terms of the per- 

 centage which do not stain with eosin 

 (and are presumably alive) in emulsions 

 of cells in a special fluid held at definite 

 pH and temperature for various lengths 

 of time. See Dead cells, Revival after 

 freezing. 



Susa fixative of Heidenhain. Corrosive 

 sublimate, 4.5 gm. ; common salt, 0.5 

 gm.; aq. dest., 80 cc; formalin, 20 cc; 

 and trichloracetic acid, 4 cc. Fix about 

 12 hrs., wash in 95% alcohol. It has 

 been modified by several people. See 

 Buzaglo. 



Swiss Blue, see Methylene Blue. 



Synapses, see methods employed by Bartel- 

 mez, G. W. and Hoerr, N. L., J. Comp. 

 Neurol., 1933, 57, 401-428. 



Synovial Fluid of normal knee joint. Method 

 of examination and results (Coggeshall, 

 H. C, Warren, C. F. and Bauer, W., 

 Anat. Rec, 1940, 77, 129-144). 



Syphilis, see Treponema pallidum. 



Taenia Echinococcus, a parasite of dogs 

 which produces hydatic cysts in human 

 liver and other tissues. The laminated 

 cyst wall is typical and the heads have 

 double circle of hooks and 4 suckers. 



Taenia Saginata. In examination of fresh 

 Feces identify by head with 4 suckers 

 but without hooks. 



Taenia Solium. Look in Feces for head 

 with 4 suckers and a circle of small 

 hooks best seen in fresh mounts. The 

 genital system opens at the side and 

 the uterus is only slightly branched. 



Tagged Atoms, see Radioactive Isotopes, 

 Deuterium. 



Tannic acid iron technique is described by 

 Salazar, A. L., Stain Techn., 1944, 19, 

 131-135. He advocates it for study of 

 Golgi apparatus and with Giemsa's 

 stain to give sharper differentiation 

 between agranulocytes and granulo- 

 cytes. 



Tantalum, see Atomic Weights. 



