If the animals are contained in 50 cubic centimetres of water it suffices to add from three to six cubic centimetres of carbonated water to make all the copepods energetically positively heliotropic.
"Darwin and Modern Science"
A.C. Seward and Others
Marine copepods can be made positively heliotropic by the lowering of the temperature alone, or by a sudden increase in the concentration of the sea-water.
"Darwin and Modern Science"
A.C. Seward and Others