I.AU OF A« I El IK \l I - . 



superior adaptability, interfere with the development of the less useful am 

 -. unl thus tend to replace them. The nee ollary of this p 



would be the m <>i' the previously existing nealogic Btages in direct |>i<>- 



the number of new characters successively introduced into the direct 

 line of modiBcation during the evolution of a group. 



The iiii of this law becomes more apparent when consideration is 



claimed for it as a working hypothesis for the explanation scure prob- 



The complicated metamorphoses of the Hymen- 



mple, in which feetless and headless 



in be attributed to acceleration, like the nunc normal examples 



-.1 Cephalopoda. They illustrate the suppression of ancestral thysanu- 



rifbrm which when present in the active larvsa of lower orders in 



were derived from i possibly similar to the adull 



ea new interest to the thi 

 cal \ Sir John 1 ted out the nsepionic 



; ysanura. 

 illy applic to the explanation of the medusalesa • 

 morphoses of the fresh-water Hydra, as compared with the marine Tubularia in 

 which the med nt, and also to the accelerated development 



of the pelagic medu n 1 others, in which the hydra-like stage has 



in Taenia, nisi ' that the secondary 



furnished with cuttin worked by Bpecial muscles, and used for d 



i h\ many naturalists, though it \s 

 phologically the remnant of an active form producing the young Taenia by an 

 involution or bud I a. ills. The am 



acquit Form with cutting blades, and then, the evolution 



reverse process of n sorption 

 of the blades by th< 

 ni'l the ii- these to be retained, while 



ther charai I i d, or else lik>- the blades 



■ 



the loss of pro 

 correlating with a highly accelerated mode of development is man himself; 1 

 and his examph in making clear what we mean by 



ion, which is often evidently due 



iturely 

 many of the normal progressive chn 

 the ni i type, in losing the prognathism of the An- 



thropo ily a highlj the adult 



n a morpholof instead <>\' 



i the brain a- compared with the lower part of the 



: dl tip- \ 



