FIELD T-2 

 Columns 58, 59, 60, and 61 



series 32-- and 35--. The only suitable item now in the Field T-2 3 series is Symbol 33, rate of 



unspecified genetic change, with which Symbol 1 or 2 of Field T-2 is used. 



Symbol 34 is used to code aberrations of the genetic structures of cells other than germinal 

 cells. In higher animals, such a mutation would not be inheritable nor, in the adult animal with its 

 finally matured tissues, would the mutation most frequently be detectable ; in plants and the more 

 simple animals, however, a somatic mutation may be inherited by the mutated part reproducing either 

 sexually or asexually and whatever vegetative or somatic tissues and organs are produced by the mutated 

 cells will reveal any anatomical or physiological changes due to the mutation. Therefore, the coding 

 of "somatic mutation" does not represent a code classification of mutations that are not inheritable by 

 having occurred in cells other than germinal cells. 



Symbols of series 32-- and 35-- (of which, to date, there are only the two general items, 

 Symbols 32 and 35) are for coding the anatomical or physiological changes in the organism which are 

 brought about by the modification of chromosome structure of the cells (whether it is germinal or 

 somatic mutation). In each of these series may be placed a limited number of items representing 

 specific anatomical and physiological deviation due to chromosomal modification. Symbols 7 (causes) 

 and 3 (prevents) are the only symbols of Field T- 1 to be used with symbols of the 32-- and 35-- series; 

 the normal incidence of such an anatomical or physiological deviation would be given a symbol of the 

 33-- series and a test compound's effect on that incidence would be coded with Symbol 1 or 2 in 

 Field T-l. 



The use of Symbol 32 and the use of Symbols 511 and 521 (adaptations which are "genetic" in 

 that the adaptations occur gradually with succeeding generations) are sometimes confusing. All of the 



items of symbol series 5 are concerned with the test organism's adapting to the test compound 



(e. g. , the test organism's becoming tolerant of or resistant to the test compound). A symbol of the 



5 series codes the adaptive effect, without pretending to distinguish as to whether it is due to a 



chromosomal mutation. In the case of Symbols 511 and 521, the symbols indicate only that a tolerance 

 or sensitivity (511, with Symbol 1 or 2 in Field T-l) or increased virulence or attenuation (521, with 

 Symbol 1 or 2 in Field T-l) were produced over several generations and there is no evidence as to 

 whether it is the result of selectivity or actual genetic mutation. If it were demonstrated to be genetic 

 mutation, the adaptation should not be coded with Symbol 511 or 521, but should be coded with a 

 special symbol added to the 35-- series. 



18. Symbols 4165 and 4166; coding of chlorosis (deficiency of chlorophyll) and abnormal depth 



of color (presumably abnormally large quantity of chlorophyll) due to, or affected by, the test 

 compound or secondary compound 



The coding of the deficiency of chlorophyll has been a problem partly because of its nature, 

 chlorosis being generally a symptom of one or another deficiency disease. Although it is possible to 

 do it by use of Symbols F824, FA24, FI24, and FE-- (coding in Field D chlorophyll as the specific 

 compound whose synthesis, deposit, withdrawal, or destruction is affected), so much general screen- 

 ing data on chlorosis was encountered that it seemed more practical and adequate to provide a special 

 symbol for the pathological condition, for sake of simplicity. The condition has been associated 

 somewhat inappropriately with discolorations (e. g. , russeting of fruits), though it actually does not 

 classify any more suitably elsewhere in Field T-2; thus, its symbol is 4165. An associated condition, 

 which has been described as a result of certain test compounds, abnormal depth of color (due presum- 

 ably to an excess of chlorophyll), has been assigned Symbol 4166. It is by these two symbols that the 

 CBCC codes all production of (and effects on ) these two conditions by the test compound or secondary 

 compound. 



19. Symbols 43, 44, 45, 46, and 47; carcinogen-induced tumors; coding of their production and 

 coding of their treatment by the test compound or secondary compound 



As indicated by the definition of Symbol 43, the production of a tumor by the test compound is 

 coded only by Symbol 43. When a tumor has been induced by a chemical or is spontaneous and is 

 SUBSEQUENTLY treated by the test compound (i. e. , treated by a chemical other than the one that induced 

 the tumor), only Symbol 44, 45, 46, or 47 may be used and the fact that the tumor was induced or was 

 spontaneous is coded in Field F by Symbol T or U. 



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