Beyerinck was led to take up the decided position just mentioned by his researches into the conditions determining the formation of plant-galls as the result of injury by insects.
Thus he demonstrated that the forms of the land exercise a directive and determining influence on climate, plant life, animal life and on man himself.
The geological structure and the mineral composition of the rocks are often the chief causes determining the character of the land forms of a region.
Logical, political and commercial development of the subject runs the determining control exercised by crust forms acting directly or indirectly on mobile distributions; and this is the essential principle of geography.
Among the later followers of Basilides, actual magic played a determining part.