NITROSAMINO REACTION 



232 



NORMALITY, MICROSCOPIC 



ammonium sulphate) 2 min., then few- 

 drops cone, ammonium hydroxide which 

 turns them purplish blue. For quanti- 

 tative unreliability of the test for -SH 

 and -S.S- see Hammett and Chapman, 

 (F. S. and S. S., J. Lab. & Clin. Med. 

 1938-39, 24, 293-298). See Sulfhydryl 

 Groups. 

 Nitrosamino Reaction of Lison (p. 161) 

 consists in transforming the amino group 

 present in pyrrol and indol into nitrosa- 

 mine by action of nitric acid; then by 

 demonstrating the nitrosamine by the 

 reaction of Liebermann. 

 Nitroso Dyes (quinone oximes). Produced 

 by nitrous acid acting on phenolic com- 

 pounds. Naphthol green B and Y. 

 NNN Medium, see Leishmania, 

 Nocht's Stain for malaria plasmodia is de- 

 scribed by Craig, p. 287 as less satis- 

 factory and more time consuming than 

 Wright's. 

 Nonfilament-Filament Ratio. This is de- 

 rived from the Filament-Nonfilament 

 Count, the number of nonfilamented 

 neutrophiles being multiplied by 100 

 and divided by the number of filamented 

 ones. See Stiles, M. H., J. Lab. & 

 Clin. Med., 1940-41, 26, 1453-1460. 

 Nopalin G, see Eosin B or bluish. 

 Normal Solutions. The equivalent of a 

 substance (equivalent weight, the gram 

 equivalent) is the weight in grams which 

 in its reaction corresponds to : a gram 

 atom of hydrogen, or of hydroxyl, or a 

 univalent ion, or to half a gram atom of 

 oxygen. A normal solution contains 

 one equivalent per liter, a 0.05 normal 

 contains 0.05 equivalent. 



Hydrochloric acid (HCl), the molecu- 

 lar weight is H = 1.008 -|- CI = 35.457 

 (see Atomic Weights) = 36.465. Con- 

 sequently make up 36.465 gms. of HCl 

 to 1 liter with aq. dest. But it can not 

 be weighed out in this way. Since 

 cone, hydrochloric acid (sp. gr. 1.19) 

 is approximately 12 N, to make a normal 

 solution (approximate) dilute 83.3 cc. 

 to 1 liter with aq. dest. The normality 

 can be accurately determined by stand- 

 ardizing with sodium carbonate, or by 

 titration with a solution of sodium 

 hydroxide of known normality. 



Sulphuric acid is H2SO4. Molecular 

 weight calculated in the same way is 

 98.08. But there are 2 replaceable 

 hydrogen atoms so that in making a nor- 

 mal solution the molecular weight is 

 divided by 2 which means that 65.068 

 gms. of H2SO4 is to be made up to 1 liter 

 with aq. dest. A cone. sol. (sp. gr. 

 1.84) is approximately 36 N. To make 

 approximately 1 N dilute 27.8 cc. to 

 1 liter. 



Oxalic acid has the formula (C00H)2- 

 2H2O with molecular weight of 126. 



Owing to presence of 2 hydroxyl groups 

 it has 2 hydrogen equivalents and it is 

 necessary to divide the molecular weight 

 by 2 so that 63 gms. is made up to 1 liter 

 with aq. dest. 



The alkali sodium hydroxide (NaOH) 

 has 1 hydroxyl group, so that the molecu- 

 lar weight is taken without division. 

 But with disodium phosphate, the 

 formula of which is Na2HP04, the 

 hydrogen equivalent is ^ NajHPOi, so 

 that the molecular weight is divided by 

 2. Similarly with the salt Na2S04 the 

 molecular weight is halved . For sodium 

 triphosphate, Na3P04, the hydrogen 

 equivalent is 3 NajPO*, or the molecular 

 weight is divided by 3. 

 Normality, Microscopic (From Cowdry's 

 Histology, 1950). Knowledge of the 

 microscopic structure of normal tissues 

 is prerequisite to an understanding of 

 their microscopic structure in abnormal 

 conditions. These latter conditions in- 

 deed are defined in terms of the former 

 by merely adding a prefix "differing 

 from," the Latin ab. Yet it is extra- 

 ordinarily difficult to reach agreement 

 on what constitutes justification for the 

 use of the adjective "normal." Dis- 

 cussion tends to drag out almost end- 

 lessly. 



Definition: We choose here to advo- 

 cate the statistical definition of normal- 

 ity. According to this : a normal condi- 

 tion is the usual one in members of a 

 homogenous group . By usual is intended 

 in the majority, that is in any number 

 over 50 per cent. By homogeneous is 

 meant in individuals who are alike at 

 least insofar that they are of the same 

 race, sex and age. 



Exam-pies: The existence of races, 

 characterized by structural differences, 

 is a fact to be reckoned with. What is 

 normal, or usual, in one may or may not 

 be normal or usual in another. Physi- 

 cal anthropologists deal with such 

 matters but histologists are also in- 

 volved because it is desirable to explore 

 microscopically differences that are de- 

 tectable by naked-eye inspection. 

 These racial differences are grafted on 

 a basic and fundamental similarity, 

 for all races of mankind belong to one 

 and the same species. Conspicuous 

 among them are certain features of 

 hair, skin and body build, which are 

 normal for one race, but are not normal 

 for others. The list on careful study, 

 may prove to be a long one. 



Between the two sexes there is like- 

 wise a fundamental similarity. Many 

 tissues of males and females are indis- 

 tinguishable. Some others show quan- 

 titative differences. The normal num- 

 ber of erythrocytes per cubic millimeter 



