SYNOPSIS. xxiu 



used by pupa in building up the organs of the imago, 276; in- 

 activity of pupa in the second series a prolongation of the 

 shorter periods of inactivity accompanying every moult, 277; 

 want of any common structural differences in quiescent and 

 active pupae, 277; quiescence, therefore, a habit of resting from 

 exertion, 277. Replacement of Thysanuriform stage in orders 

 XII.-XVI. by secondary larval stage* in accordance with law 

 of acceleration in development, 278; tendency toward accelera- 

 tion shown in the more speciahzed forms of the orders I.-TX., 

 278; adult characters inherited by certain Orthoptera, 278. 

 Extraordinary importance of the functions of larval life in orders 

 XI.-XVL, 278. Larval life less variable than the adult stage in 

 many other classes of animals, 278; in insects larval life as effi- 

 cient for the manifestation of new modifications as the adult 

 stage, 278, 279; modifications probably due to the plastic nature 

 of the organism in adapting itself to its surroundings, 279; 

 parasites as good illustrations, 279; extraordinary metamorpho- 

 ses often accompanied by corresponding acceleration and loss 

 of primitive stages, 279, 280. Transformation of Echinoder- 

 mata, 280; adaptations of the larvae to a free life in the water, 

 280. Explanation for the hypermetamorphoses of Epicauta, 

 Sitaris, Meloe, etc., 280. Laws of heredity subservient to the 

 effects of habit and use of parts, 280. Degraded character of the 

 secondary larval forms, apparent rudimentary condition of these 

 forms, 280, 281. Argument offered against the derivation of 

 Coleoptera from Thysanura, 281 . Researches of Brauer, Packard, 

 and Lubbock, 282. Composite nature of the process of indirect 

 development, 283; stages of development in individuals are 

 abbreviated records of the stages of evolution in the history of 

 the group to which the individual belongs, 283. Specialized 

 forms in each group evolved from generalized forms, 283. I>ater 

 acquired and useful characteristics replace primitive and useless 

 characters, 284; law illustrated by sucking mouth parts of 

 Hemiptera, adult characters in larval locusts, and the Pupipara, 

 284, 285. Adult and pupal characters remarkably constant in 

 orders X.-XVL, 286. Lubbock's views on the rank of meta- 

 morphoses, 286. Confusion caused by the use of the words 

 "higher" and "lower," 287, 288; reasons why they should not 

 be used, 288. 



