HEREDITY OF ACQUIRED CHARACTERS 201 



parsnip are subsequently formed, they too partake of the in- 

 fluence. 



If it were not so, not even the tendency to produce a large 

 and fleshy root would be hereditary or, as it is suggested, 

 " strengthened by selection ". 



The same sized root could only be reproduced as that of 

 the original parent. 



I will now give an interesting case from, the structure of 

 tendrils. 



The Virginian creeper of America (Ampe/opsis hederacea) 

 bears a branched tendril, homologous with, that is formed out 

 of, flowering branches. Each little branchlet terminates in a 

 hooked point. As soon as one of these hooks catches a de- 

 pression in a rough wall the irritation induces it to swell and 

 grow into an adhesive pad ; which is never formed unless con- 

 tact is secured. 



In the Japanese species {A. Veitchii) the tendril develops 

 half- formed pads on the tips of its branchlets, before any contact 

 has been made with the wall. 



They can only become effectively adhesive after contact 

 has taken place. 



The first-named species proves that the merely mechanical 

 contact is necessary for the very commencement of the develop- 

 ment of the pads. 



The second proves that the tendency to produce them is so 

 strongly hereditary, that they now appear without any contact 

 at all ; i.e., the actual modification itself is, therefore, heredi- 

 tary, and only requires contact to perfect it, so as to become 

 an adhesive organ. 



A similar difference resides between genera of Bignoniacece 

 as Darwin has pointed out.^ 



The few cases I have given are but samples. Similar lines 

 of inductive evidence can be applied to all the organs of plants 

 — and it might be added to animals. Experimental proof is 



^ Climbing Plants, p. 102, note. 



