212 EXPERIMENTAL EVOLUTION LECT. 



with common pure water starch is never or but rarely 

 present in the root at the period when it is generally 

 eaten, plants of the same age watered with solutions 

 of common salt (from I to 20 per thousand) do con- 

 tain a great deal of starch under certain conditions. 

 For instance, if the water contains 20 per mille of 

 salt, or i or 2 per mille, there is no starch ; at 3 or 

 5 /oo tnere is little of it ; at 10 % a little more, but at 

 4 /oo there is a large amount of starch. Thus, the 

 presence of common salt, in definite proportions, exerts 

 a considerable influence on the chemical structure and 

 physiology of the plant. 1 With Lepidium sativum 

 things are somewhat different : while the plant con- 

 tains normally a large amount of starch, watering 

 with a solution containing 10 / 00 or more of common 

 salt causes the starch to diminish in a large measure 

 and even to disappear totally, while weak solutions 

 do not interfere with the proportions of this sub- 

 stance. 2 



1 Cf. Lesage : Sur la Quantite d'Amidon contenue dans les Tuber- 

 cules du Radis. Comptes Rendus, September 7, 1891. 



2 Cf. Influence de la Salure surla quantite de f Amidon contenue dans 

 les Organcs vegetatifs du Lepidium sativum (Comptes Rendus, April 20, 

 1891), and two other notes in the Comptes Rendus, January 18, 1892, 

 and March 31, 1891. I would also refer the reader, on this general 

 subject i of 'the influence of salt on structure and physiology, to A. 

 Batalin : Wirkung des Chlornatriums auf die Entwickelung von 

 Salicornia herbacea (International Meeting of Botanists and Horti- 

 culturists in St. Petersburg, 1884) ; and to C. Brick : Beitrage zur 

 Biologic tind vergleichende Anatomie der baltischen Strandpflanztn 



