INTEODUCTOKY. ^5 



lirst few segments, where one of them has given rise to eye- 

 like markings ; a series of oblique stripes, quite unconnected 

 with the longitudinal ones, have appeared. An important 

 result of these observations, which were carried out with a 

 large number of species of Hawk moths, is that the same 

 markings are repeated in the same order in allied forms ; one 

 stage or other may be omitted, but the oblique stripes never 

 precede the longitudinal striping ; nor does any caterpillar 

 commence life with one of the later developed characters and 

 recur to one of the earlier. 



Dr. Weismann considers that this series of stages, which is 

 more complete in some forms than in others, is an indication 

 of former influences that have been at work ; originally, for 

 example, a longitudinal striping was advantageous to such 

 caterpillars, perhaps for the reason, as it has been ingeniously 

 suggested, that monocotyledonous plants were more abundant in 

 former epochs of the earth's history. The ribs on the leaves 

 of these plants are arranged longitudinally, and therefore a 

 caterpillar with a similar striping would be less conspicu- 

 ous ; even now it is found that grass-feeding caterpillars are 

 very generally longitudinally marked ; for instance, those of 

 such butterflies as the Meadow Browns and Gatekeeper. 

 When these markings ceased to be useful, others more in 

 accordance with the surroundings were developed ; but a 

 residue of the original coloration, only preserved in the earlier 

 stages, is left to tell the history of the species ; this, at least, 

 is the case as to some species ; others have, on the contrary. 

 remained at a stage of coloration, which is, ex hypothesi, dis- 

 advantageous. Dr. Weismann mentions a remarkable Sphinx 

 larva preserved in the Berlin Museum, which appears to have 

 remained of a uniform colour throughout the greater part of 

 its life. Green was no doubt the earliest colour of these cater- 



