FIELD J 

 Columns 37, 38, 39, 

 40, 41, and 42 



If it is desirable to maintain this excised part of the host for any period of time, a nutrient 

 solution or saline bath, etc. (i. e. , a "secondary host") is frequently necessary. For this reason, a 

 second coding area for this "secondary host" would appear useful. Because occasions have been so 

 few when the CBCC needed a second coding field for such a secondary host, it has not been considered 

 practical to reserve IBM punched card space for it. Therefore, having only one field for hosts, Field J 

 is coded with the host organism donor of the excised part (as described in the previous paragraph), 

 while the bath or nutrient solution (the "secondary host") can not be coded (except that sometimes 

 coding in Field S-3 [Symbol C] implies the presence of a bath- -when the test compound is applied in 

 the bath). However, when an excised part used as a host (ordinarily indicated by Symbol R of Field L) 

 is placed in a "secondary host", always code Field L with Symbol T. It is necessary to include in the 

 written abstract for Field L the specific solution, bath, etc. , which plays the role of secondary host. 



2. Tumor hosts 



The discussion and description of the Tumor Code of Field E includes an explanation of tumor 

 hosts and the use of Field J. Regardless of the organism in which the tumor originated, the organism 

 in which the tumor is located at the time of the chemical test is coded in Field J. Thus, for chemical 

 tests using transplanted tumors, the species and strain of the organism into which the tumor was trans- 

 planted for the test is coded in Field J. 



In accordance with this procedure, any non-living host (nutrient medium, saline bath, etc. ) in 

 which a tumor (or tumor slice, brei, etc. ) is maintained during a chemical test is coded in Field J, 

 regardless of the organism in which the tumor arose. 



When a compound is tested to produce a tumor (i. e. , tested for carcinogenicity), the coding of 

 this action is accompanied with an entry in Field J which is always the organism in which the compound 

 was tested. 



3. Non-living materials: discrimination between their uses as HOSTS and as mere CONVEYERS 

 OF THE TEST COMPOUND 



Most often it is not difficult to distinguish between a non-living material which serves as a 

 host to the test organism being treated and the other non-living materials or instruments used in the 

 experiment. A non-living host is ordinarily a material on or in which the test organism normally is 

 found, either permanently or occasionally, or it is a material which serves directly to nourish and 

 sustain the test organism ; in either case, the material is representative of the organism's normal 

 environment, however artificial may be the nutrient or sustaining medium. 



For example, in an experiment in which the test compound is a gas bubbled into an aquarium 

 where algae are the test organisms, the host is the material constituting the normal intimate envi- 

 ronment of the test organism--i. e. , water; it is not the tube leading the gas to the water, nor the 

 glass aquarium housing the algae and water. Again, in experiments in which the test compound is 

 deposited on or in a material (glass, wood, cloth, etc.) which flies (as test organisms) are induced 

 to contact or on which are placed lice (as test organisms), the glass, wood, cloth, etc. , are properly 

 regarded as hosts, since they were selected as representative of environmental surfaces which the 

 test organism might normally contact. In an experiment in which a test compound mixed with an 

 attractant is placed in a glass dish in a cage of flies, the glass can not be regarded as the host 

 material but merely as the container of the test compound and attractant (in the same way as the tube 

 of the aquatic experiment was only the conveyer of the test compound); in this situation there would 

 be no entry in Field J. 



In any experiment in which a volatile test compound is deposited on a material (or placed in 

 an open container) and in which the chemical acts as a gas diffused through the air, the material or 

 container on or in which the chemical is deposited is not a host, but merely a conveyer; the host is 

 the treated air. Similarly, if a water-soluble compound is deposited on a material (glass or cloth, 

 e. g. ) which is subsequently immersed in water to treat aquatic organisms, the water is the host to be 

 coded in Field J and the material on which the test compound was deposited is merely the conveyer. 



A written record of the conveying materials and instruments should be included in Field J as 

 well as the actual host materials. 



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