10 Descent 



concerning the real nature of species in the wild 

 state. The other part rests on my own obser- 

 vations and experiments, made in the botanical 

 garden of the University of Amsterdam. 



For many years past I have tried to elucidate 

 the hereditary conditions of species and varie- 

 ties, and the occasional occurrence of mutations, 

 that suddenly produce new forms. 



The present discussion has a double purpose. 

 On one side it will give the justification of the 

 theory of mutations, as derived from the facts 

 now at hand. On the other hand it will point 

 out the deficiencies of available evidence, and 

 indicate the ways by which the lacunae may 

 gradually be filled. Experimental work on 

 heredity does not require vast installments or 

 a costly laboratory equipment. It demands 

 chiefly assiduity and exactitude. Any one who 

 has these two qualities, and who has a small 

 garden at his disposal is requested to take part 

 in this line of investigation. 



In order to observe directly the birth of new 

 forms it is necessary, in the first i3lace, to be 

 fully clear concerning the question as to what 

 forms are to be expected to arise from others, 

 and before proceeding to a demonstration of the 

 origin of species, it is pertinent to raise the 

 question as to what constitutes a species. 



Species is a word, which always has had a 



