70 RELATIONS OF PLANTS TO WATER 



their frequency on the roots. Compute the number per square 

 millimeter. Grow a second lot in water cultures. Compare the 

 features of the root-hairs mentioned above. 



Collect living specimens of Ranunculus delphinifolius Torr. 

 (Ranunculus multifidus L.). Note that the long stems carry two 

 forms of leaves. Those under the surface of the water are 

 divided into numerous capillary segments, while those in the air 

 are divided into three to five broad lobes. Examine the structure 

 of both kinds by means of cross sections. Describe the charac- 

 ter of the epidermis with especial attention to stomata in both in- 

 stances. If possible grow specimens in water and note the man- 

 ner of formation of the two forms of leaves. Similar observations 

 may be made on Sagittaria. 1 



1 Schenck, H. Vergleichende Anatomic der submersen GewSchse. Bibl. Bot. i : 

 I. 1886. 



