372 



APPENDIX D. 



IV. — Moss ivaterfrom the neighbourhood of Schleissheim. — 

 Dr. Wittstein. 



APPENDIX E (page 108). 



VEGETATION OF LAND PLANTS IN THE WATEET SOLUTIONS OF 

 THEIE FOOD. 



In experiments on the vegetation of land plants in the watery 

 solutions of their food, great attention must be paid to the ten- 

 dency of the fluid to become alkaline by the process of vegeta- 

 tion, as land plants always die in alkaline solutions. Great care 

 must therefore be taken to keep the fluid neutral (very faintly 

 alkaline) or feebly acid. Knop attained this object by fre- 

 quently transferring his plants to fresh solutions ; Stohmann, by 

 placing the plants from the commencement in feebly acid solu- 

 tions, and at a later period transferring them sometimes to 

 fresh solutions, and at other times removing the alkaline reac- 

 tion by frequent addition of a small quantity of acid. 



The tendency of solutions to become alkaline by means of the 

 plants vegetating in them, and the injurious effect of an alka- 



