Inheritance of Acquired Characters 
blossomed, and, taken altogether, there was no 
appreciable difference from O. repens, L.” 
From this experiment Professor Henslow draws 
the inference that acquired characters tend to be 
inherited in plants. In our opinion the ex- 
periment affords strong evidence against the 
Lamarckian doctrine. Here we have a plant 
which has, perhaps, for thousands of generations 
developed spines owing to its dry environment. 
If acquired characters are inherited we should 
have expected this spiny character to have 
become fixed and persisted under changed 
conditions, for some generations at any rate. 
But what do we find? By the second year the 
thorns have entirely disappeared. All the years 
during which the plant was exposed to a dry en- 
vironment have left no stamp upon it. The fact 
that the new branches of the first year’s growth 
bore small spines is not, as Professor Henslow 
asserts, proof of their hereditary character. It 
merely shows that the initial stimulus to their 
development occurred while the plant was still in 
its dry surroundings. 
In the same way all other so-called proofs of the 
heredity of acquired characters break down when 
critically examined. 
In our opinion “not proven” is the proper 
verdict on the question of the possibility of the 
inheritance of acquired characters in the higher 
animals, One thing is certain, and that is that 
23 
