Abstract
Summary
Certain clones of Paramecium produce substances that kill certain other clones of Paramecium. The former clones have been called “killers” the latter “sensitives”. The toxic substances have been called “killer substances” or “paramecins”. The present paper describes 2 killer substances produced by Paramecium bursaria.
Paramecin 22: This killer substance produced by clone Ru22 had the following effects on clone Enl: sluggishness, apparently as a result of the slowing up of ciliary action; darkening of color; distortion of form; stickiness of surface, leading to pairing or clotting of the animals; nuclear changes in paired and clotted animals, and in some single animals; death.
Paramecin 34: This killer substance produced by clone Mi34 had the following effects on clone Enl: darkening of color; unusually active movements; swelling, developing of blisters, bursting; death. No nuclear changes were found.
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