摘要:

Under experimental conditions fully embryonated eggs ofTrichocephalus vulpishatch in the small intestine of dogs within 30 min. after the eggs are fed. The larvae penetrate the intestinal mucosa within 24 hr. after infection and at that time may be found deeply embedded. Between 48 and 96 hr. after infection the larvae become coiled and sluggish, and the majority are found lying at the base of the crypts of Lieberkühn in the upper levels of the small intestine. They do not work their way back to the lumen of the intestine for at least eight days, although there is some evidence that they may return to the lumen by the 10th day after infection and are then carried passively down to the large intestine. There is some minor tissue destruction by the larvae during their mucosal penetration.

ISSN:1923-4287    

DOI:10.1139/cjr47d-001

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Impregnated filter paper, and coated glass substrata, as well as direct spraying techniques were employed to test the relative toxicity of several organic molecules related to DDT, as contact insecticides against adultDrosophila melanogaster. Anaesthetizing the flies for convenience of handling did not affect observed mortalities. In general both impregnated paper and coated glass (vial) techniques gave reproducible results. The former resulted in an unexplained drop in mortalities above a certain dosage level, the latter gave somewhat more uniform results. Direct spraying was superior when the chemical had a fumigant effect also.γ, 1,2,3,4,5,6-Hexachlorocyclohexane and the difluoro analogue of DDT, alone out of 18 chemicals tested, exceeded DDT in effectiveness. The γ isomer of 666 exhibited a strong fumigant but also a long residual effect while the difluoro analogue lost toxicity rapidly.Removal of one or both phenyl chlorine atoms from the DDT molecule, or alteration of theirp-ppositions, or their substitution by any radical other than F, interference with the trihalogen group of DDT, or the introduction of a double bond into the molecule, all seriously affected the insecticidal action of the DDT. Arranged from the most to the least toxic, the halogen analogues of DDT have the following order: fluorine, chlorine, bromine, iodine.

ISSN:1923-4287    

DOI:10.1139/cjr47d-002

出版商:NRC Research Press    

年代:1947

数据来源: NRC