therapeutic management of neoplastic occlusions of the colon the authors present their experience in 39 cases of occlusions occuring in a number of 142 neoplasies of the colon hospitalized between 1965 and 1973 the major attention was given to the treatment of the occluding complication in cases where the occlusions are due to neoplasies of the right colon right hemicolectomy should be carriet out in preference while in cases with neoplastic occlusions of the left colon the attitude will be differentiated the authors are not partisans of the emergency left hemicolectomy lung clearance of particles in two strains of rats two strains of commonly used experimental rats were compared with regard to lung clearance of tio2 particles the fisher 344 inbred rats retained predictably fewer particles after a 7hr exposure than the larger outbred longevans rats this fact can be expected in view of the different lung size of the two strains in addition clearance of the retained particles was significantly slower in fisher 344 rats differences in lung clearance capacity of different animal strains should be considered when experiments in inhalation toxicology are performed