FIELD T-2 

 Columns 58, 59, 60, and 61 



evidence of the compound's lethal effect on the individual , since there is frequently no way of deter- 

 mining the quantity of test compound that reached the individual. Both of these aspects contributed to 

 a reluctance to code the arthropod response with any of Symbols 11, 111, and 112. 



A third difficulty arose from the way in which the results of such tests on arthropod infestations 

 are frequently expressed. While the effect might be expressed in terms of the percentage reduction of 

 the arthropods, it is frequently expressed in terms of the percentage of the hosts or host cleared of 

 arthropods. In the case of infectious pathologies, such an effect expressed in terms of the host is 

 coded only with symbols of the 17-- series; originally, this was the only existing way to code the test 

 compound's clearance of the host of an arthropod infestation, inasmuch as symbols of the 18-- series 

 were restricted to organisms on non-living hosts. However, the CBCC was reluctant to regard these 

 insect infestations of living organisms (ordinarily infestations of plants) as being diseases of the living 

 organism and to code the amelioration of infestations by insects with symbols of the 17-- series. This 

 was in part because insect damage to organisms, while academically representing pathology by the fact 

 of the damage, does not fall within the general concept of disease entities caused by microorganisms 

 and true parasites, in the same way that wounding of a man or other animal by a dog (to draw an 

 exaggerated analogy) is not ordinarily regarded as being diseased by the dog. Furthermore, so many 

 data are available from insecticide tests falling within this description that at one time it seemed likely 

 they might lead to engorgement of the 17-- symbol category in the punched card files, to the ultimate 

 detriment of retrieval facility. 



As a solution to this dilemma, Symbol 13, 131, and 132 have been introduced for such arthropod 

 tests. 



Observe that the definitions do not specify "death", but only reduction of the infestation. This 

 does not mean that if death is demonstrated to be the cause of the reduction of infestation, Symbol 13, 

 131, or 132 can not be used; death produced in insects infesting living organisms when treatment is 

 given to the infestation is never coded by Symbol 11, 111, or 1 12. 



Occasionally, the manner of treatment plays a role in determining whether to use symbols of the 

 13-- series or Symbol 11, 111, or 112, even when an arthropod is on its living host; if the "infestation" 

 is restricted to a single individual or a very few individuals and if administration is by some method 

 directly to that arthropod and only to the arthropod individual, any lethal effect to the arthropod should 

 more reasonably be coded with Symbol 11, 111, or 112 than with Symbol 131 or 132. This is suggested 

 because such a treatment so little resembles a treatment designed specifically to affect an infestation, 

 but more nearly resembles a test for the individual's vulnerability to the test compound. Such a situ- 

 ation might conceivably exist when the individual arthropod is maintained on its host only because the 

 arthropod is of such a nature that its normal existence is dependent on remaining in contact with its 

 living host. 



The symbols of the 13-- series are intended to supplement Symbols 11, 111, and 112 and to be 

 analogous to symbols of the 17-- series. Both of these series represent only a single direction of the 

 action, the decrease of the test organism by its death (in the case of the 17-- series, this decrease is 

 implicit by the definition of relieving the host of a pathogen). Therefore, symbols of series 13-- also 

 are defined to indicate only a single direction of action, decrease of the arthropod infestation. This 

 means that, as in the case of Symbols 1 1, 111, and 112, and symbols of the 16-- and 17-- series, 

 Symbols 1 and 2 of Field T-2 are never used with the 13-- series, but only Symbol 7, 8, 9, or A of 

 Field T-l. The probabilities of a test compound, selected for testing to reduce an arthropod infestation, 

 acting in the opposite way (in some way facilitating or increasing the degree of arthropod infestation) 

 are so remote that it has not seemed worth inserting a special symbol series to accompany the 13-- 

 series for coding such an exacerbating effect in the way that symbol series 16-- has been included to 

 accompany the symbol series 17--. 



1 1. Symbol 14; coding of Field T-2 when the biological response is expressed by the author only 

 in terms of one of the general categories of Field T-3 



The purpose of Field T-3 is distinguished in the introductory section discussing Field T in 

 general and described in the section dealing with Field T-3 specifically. 



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