ii6 The Ottawa Naturalist. [September 



tergreen and Pyrola were submitted, their low-g-rowing habit and 

 leathery leaves being the characters of similarity. 



In like manner, members of the Grass Family were to be 

 identified by the two-ranked leaves whose sheaths are split on the 

 side of the stem opposite the blade. From this character, wheat 

 and oats were recognized as grasses. The former was named as 

 that member of the Grass Family that contributes most food for 

 man. A question as to the staple food of the people of China 

 and of India led the class to see that the pre-eminence 

 belongs to rice. The leader had to tell them that rice is a 

 grass, as none had ever seen it growing. In Nature Study our 

 great aim is to walk by sight, not by faith ; but it is often 

 necessary and quite allowable to get information second-hand, 

 especially when it is based on intelligent first-hand knowledge. 

 We thus learn from the researches of others that the Grass Family 

 stands first and Pulse Family second in the amount of food con- 

 tributed to man. It was left as an undecided question as to the 

 order of plants that has the third place, but the member of the 

 class who was regarded as the oracle, declared that either the 

 Rosaceae or Solanaceae occupy this grade. 



The centre of interest of the Pulse Family was the nodules 

 that are found on the roots of the different species. In one par- 

 ticular most plants resemble Coleridge's Ancient Mariner who was 

 perishing with thirst though there was " Water, water, every- 

 where." Plants grow in an ocean of nitrogen, which element they 

 require for their proper development. Though there is, in the 

 atmosphere, nitrogen, nitrogen everywhere, the plants are unable 

 to assimilate it in the free state. Now the tubercles on the roots 

 of leguminous plants are the homes of minute organisms called 

 Rhizobia, which are free-nitrogen-assimilating bacteria, and by 

 whose instrumentality these plants are able fo incorporate the 

 necessary nitrogen A pedagogical moral to be drawn from the 

 foregoing, is that teachers of plant study should encourage their 

 pupils to dig for their information, — to examine the root as well 

 as the stem and the leaves. 



