ULAfl 'in flic Oriijin <>f Frt-xlurittfr I'attnat. \ ]:', 



The Tracheata fuini.-h sonic inl cresting exceptions which, like moat exceptions 

 tn ;i general rule, lend a helping hand to its interpretation. A young cockroach, 

 I'm- instant , with nearly all the parental characters, yet it is a less special- 



form than a butterfly, whieh starts in life as an humble grub, and long remains 

 so. Still, even in the Insecta, we find the highest forms, such as bees and ante, 



poning a free existence till the larval state is passed. Taken broadly, then, the 

 men! that the higher the organism the more advanced the stage at which it 



is upon a free and independent existence, may be regarded as a sound gene- 

 ralization. We may next seek for an explanation of this rule, and we begin by 

 the inquiry What is the use of the more complex organization of a higher form to 

 it, and how has it been produced ? Its use, or one use, is to give an advantage in 

 the 't> for i :.' ; and it has .been evolved by the constant superposition 



of successful inherited varietal modifications. This much being admitted as it 

 is uiii\ .illy admitted by modern naturalists it is clearly a disadvantage fora 

 lii-!il\ - i-.ini/ed animal to produce young which have to start afresh from 

 the same level as the inferior competitors, which it has already distanced in the 

 race, to repeatedly fight the same battle over again, or to run the gauntlet in its 

 onti tgenetic development of other competitors in each and every of the less highly 

 states through which it has passed in its phylogenetic history. As a 

 gastrula, it would have to compete with other gastrula?, and not with gastrulae 

 only, but with >hler and more formidable competitors, more advanced in their 

 development than itself. Not only would it be exposed to the dangers of direct 

 competition, but also those of the inorganic world to the violence of currents in 

 particular. The very fact that the adult possesses a higher organization is a 

 proof of the less efficiency of the lower organization which marks its earlier 

 embryological stages. Thus it would be clearly of immense advantage to the 

 race for the organism (1) to abbreviate its larval history ; (2) and to pass through 

 that history in a state of seclusion withdrawn, as far as possible, from the acci- 

 dents and competition of the outer world. 



On the higher forms these advantages are always conferred, so that a great part 

 of their development takes place in concealment, and many larval stages arc passed 

 through with surprising rapidity, or even smbstantially curtailed. 



But the more complete the seclusion of the developing animal, the less the 

 possibility of its obtaining food by its own exertions, and hence food must be 

 provided for it.* 



In the lower forms of life in which a free larval state is the rule, the resources 

 of the parent are greatly taxed in producing a vast number of embryos, compara- 



* Probably the appearance of secondary nourishment in connexion with the ovum was the firot 

 variation to occur, and secluded development followed as an effect. The advantage which 

 conferred insured more certain survival and continued variation in the same direction. 



l: -2 



