OTHER THEORIES OF SPECIES-FORMING. 273 



covered by the flesh for awhile in this process, and during 

 this time be incapable of use. With Fierasfer, the fish that 

 lives in sea-cucumbers (Holothurians), the anus lies far for- 

 ward in the throat so that the fish has only to thrust its head 

 through the anus of the sea-cucumber in order to void its 

 faeces. How can use of the intestine or its peristaltic move- 

 ment have produced such a remarkable change in position 

 of the anus ?" Plate T offers other similar examples of adap- 

 tations inexplicable by Lamarckism, and justly says that 

 hundreds of others could be adduced. He presents suc- 

 cinctly the possibilities of Lamarckism, the inheritance of 

 acquired characters being granted, as follows : 

 Lamarckism could explain 



(1) many indifferent characters: example, changes of 

 temperature produce proportional changes in the 

 colour-pattern of butterflies' wings ; 



(2) many simple adaptations of active organs: example, 

 a muscle becomes stronger through use, and creates 

 a crest on a bone through pulls ; 



(3) some simple adaptations of passive organs (so-called 

 direct adaptations) : example, in the whales, the 

 water might directly affect the skin and sub-cutane- 

 ous tissue and thus produce the loss of hair and the 

 layer of fat. 



Lamarckism could not explain 



(1) many characters of active adaptation, even though 

 of simple kind : example, the penetrating of the lung- 

 sacs of birds through hair-fine holes into all the 

 bones ; 



(2) many complicated adaptations of active organs : ex- 

 amples, light-making organs, eyes, smelling-organs, 

 auditory organs ; 



(3) all complicated passive adaptations: example, mim- 

 icry. 



Even if we are ready to admit the possibility or actuality 



