The Zoologist — August, 18G7. 841 



Lel/crs on Variation in Lepidoptera. By Edward Newman. 

 Letter the Second. — Alternation of Generations. 



My clear Mr. Wollaston, 



The theory of alternate generations or avism is exceedingly 

 simple; it is that the child shall more closely resemble its grand- 

 mother than its mother : the male parent is not supposed to contravene 

 this rule, but there is less certainty in investigating the phenomena : 

 take an illustration of this, a female butterfly or moth is observed in 

 the act of oviposition ; we are liable to no mistake about the female 

 parent, but are utterly ignorant of the male, the same with many of 

 our domestic animals, as cats or house-dogs : now giving a designat- 

 ion, as B to the female moth, the female cat, or female dog, the 

 theory would suppose the progeny of each (which may be designated 

 as c), to resemble the grandparent (a) more than the parent (B), and 

 therefore that a series of generations would exhibit certain characters 

 alternately, thus : — a B c D e F g H i K 1 M n O : those generations 

 designated by small letters possessing certain characters in common, 

 and those designated by capitals possessing certain other characters 

 in common. 



It will at once be seen that this theory has a direct tendency to sub- 

 vert the Lamarckian hypothesis of evolution, because the same series 

 of generations can scarcely possess two opposite propensities, the 

 propensity to change to something new, and the propensity to revert 

 to something old ; but this phase of the inquiry may be dismissed for 

 the present, for it must be obvious to every one capable of reflection 

 that so abstruse a question requires a more careful and critical 

 examination than can be given it here. Be this as it may, a belief in 

 the tendency to recede to a prior character is no hypothesis, since it is 

 exhibited throughout the organized world, and is familiar to all 

 breeders and to all naturalists. Professor Huxley, in his Lectures on 

 the "Phenomena of Organic Nature," has entered fully into the 

 subject, and has shown, beyond all possibility of dispute, that this 

 tendency is universal, but that it is. methodical also: it is called 

 "atavism,"* and may be simply defined as a struggle to revert from 

 recent change to the characters of a great-grandfather or great-grand- 

 mother, indeed to revert to some distant ancestral type. But the 



* From alavus, a great grandfather or grandmother. 

 SECOND SERIES — VOL. II. 2 S 



