Hermon C.Bumpus, « The variations and mutations of the introduced sparrow. Passer Domesticus », Biological Lectures delivered at The Marine Biological Laboratory of Wood’s Holl,Boston, Ginn & Company, 1898, p. 14.
The relation of the ovum to the complete egg is practically the same as that of a « caddis-worm », to its « case. ». The preferred material may be bits of straw, but, in the absence of straw, smallpieces of wood may be made to answer. The « worms » in the « cases » of wood are themselves not different from their, perhaps more fortunate, neighbors in straw « cases. » It is only when they adopt the wood in preference to the straw that an ontogenic makeshift becomes a phylogenic variation. New building material does not make a new architect.