40 



in alcohol and treated with water, is seen to have a characteristic 

 radial appearance, much like the ribs of an umbrella. The water 

 must be carefully added or this will not be seen. 



The palisade cells are of a deep brown color and this is changed 



Figure 35 

 Fig. 35. Charlock. 



to a blood red when cross sections are heated slightly with a so- 

 lution of chloral hydrate. This reaction is characteristic of 

 charlock. (Fig. 35.) 



RIB GRASS. 



{Plantago lanceolata, L.) 



The seeds of rib grass as well as of other species of plaintain 

 are very often found in the examination of foods, but each is so 

 different in structure that by the use of a hand lens it is very easy 

 to identify them. The seed of Plantago lanceolata is shaped like 

 a double ended canoe. In length the seed varies from 1.5 — 

 2.5 m.m., seldom, however, reaching the latter size. In color 



Figure 36 

 Fig. 36. Rib Grass. 



