. Evolution and animal life; an elementary discussion of facts, processes, laws and theories relating to the life and evolution of animals . FIG. 75.—Diagram showing variations in elytral pattern of the Californiaflower beetle, Diabrotica soror. (After Kellogg and Bell.) to show the spines. In eighty-nine individuals of this speciesof locust collected at Ithaca, N. Y., the number of spines in the outer rov,T of the right tibiaevaries from nine to fifteen,in the inner row from elevento sixteen. One not given tothe systematic study of insectsmay think spines on the hindlegs very trivial structur
. Evolution and animal life; an elementary discussion of facts, processes, laws and theories relating to the life and evolution of animals . FIG. 75.—Diagram showing variations in elytral pattern of the Californiaflower beetle, Diabrotica soror. (After Kellogg and Bell.) to show the spines. In eighty-nine individuals of this speciesof locust collected at Ithaca, N. Y., the number of spines in the outer rov,T of the right tibiaevaries from nine to fifteen,in the inner row from elevento sixteen. One not given tothe systematic study of insectsmay think spines on the hindlegs very trivial structures in-deed; but the entomologist,using exactlv such character- O *j istics as the number of thesestructures as a means in help-ing him to distinguish anddefine his species, knows howconsiderable this variationreally is. The dog-days cicada () also has spines on its hindtibiae, but only a few, usually,indeed, two. But in any series of individuals of this insect some individuals will be found withbut a single spine, some with three, and a few with four even,although the very great majority will have two. For example,. FIG. 76.—Diagram showing variation inpattern in the yellow jacket, Vespa ger-manica. (After Kellogg and Bell.) VARIATION AND MUTATION 135 in a series of 98 male individuals collected at Indianapolis, In-diana, at one time, 12 individuals had one spine in the outer rowof the right tibiae, 83 had two spines, 2 had three spines, and onehad four spines. In the outer row of the left tibiae of the sameindividuals, there were three spines in 6 individuals, two in 75,and one in 17. In the inner rows of tibial spines in these same
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