Adaptations in Tissue Structure 203 



ment of even a single species, and still less, if that is 

 possible, concerning the true mode of procedure of this 

 natural selection which is so difficult to control. So that 

 we must content ourselves with putting forward the views 

 which we have just outlined merely as further con- 

 jectures speaking in favor of the Lamarckian theory, 

 without seeking to attribute to them the value of logical 

 proof. 



Structural relations in general and the most remark- 

 able ones in particular, such as the static structure of 

 bone, of certain tendons, of certain membranes, the 

 dynamic structure of the smooth and striated muscle 

 tissues and other similar formations, which represent the 

 most perfect functional adaptation and the best utilization 

 of the material down to the minutest and most delicate 

 details, testify likewise in favor of the transmissibility 

 of acquired characters. "All these formations of con- 

 nective tissue, muscle and bone," writes Roux, "could 

 never have been developed in such regularity and com- 

 pleteness by Darwinian selection from individual varia- 

 tions of form, since here there must necessarily have 

 been thousands of fibers and cellules already accidentally 

 arranged in this purposeful fashion in order to produce 

 even the smallest advantage appreciable in the economy 

 and capable of being acted upon by natural selection, and 

 so much the more since in the extremity of hunger these 

 would be exactly the parts, the heart excepted, which, 

 thanks to the small amount of metabolism in them, 

 would suffer last of all, much later than other more 

 vitally important organs with more active metabolism. 

 These formations could not therefore arise from the 

 selection of individual variations in form, but are rather 

 derived only from those qualities of the respective tissues 



