58 



LEMNA. 



[CH. Ill 



FiQ. 10^. Exp. 77. 



Fig. 10 -4 gives the comparative result of culture in 

 Sachs' fluid (8) and in the same without phosphates 

 (P). Four or five weeks (in May) are necessary to give 

 the result. Owing to an accident the figures do not 

 show the strong growth of roots in (8)\ 



(78) Calcium oxalate formation. 



The leaves of the HorserchestQut, JEscvlus hippo- 

 castanum, of Acer negundo, Uhnus campestris, and 

 Humulus lupulus are according to Schimper' useful to 

 demonstrate the fact that calcium oxalate accumulates 

 in leaves with age. To make this out, young and old 

 leaves of some of these species should be compared. The 

 method described in Chapter V. of detecting small amounts 



' In both cultures there were originally 6 plants each with 3 fronds. 

 2 Botan. Zeitung, 1888, p. 83. 



