l6o NATURE STUDY. 



She showed me that some of the openings were small, and 

 others as much as eight inches across. In no case was 

 the hood of the plant on a level with the surface of the 

 ground. In the larger ones the cavity was widest at the 

 bottom, the snow walls forming an arch over the top. 



"While we were talking the thermometer had been re- 

 gistering the temperature of one of the plants. She gent- 

 ly drew it forth and read its record. This she jotted down 

 in her note-book against the date. She then let me look 

 at her notes. 



We found that the temperature of the plant was, in many 

 cases, considerably above that of the atmosphere. The 

 largest difference between the two was four degrees, Centi- 

 grade, or seven and one- fifth degrees, Fahrenheit. 



" ' I thought when I first noticed those holes, ' said she, 

 'that the skunk-cabbages must be at work generating 

 enough heat to melt the snow around them. Now I am 

 sure of it. I have visited this place every day for a week, 

 and my record shows that the plant not only keeps from 

 freezing itself, but is able to melt out a breathing-hole be- 

 sides.' '" 



A scientific writer has recently explained that the sense 

 of gravitation in plants is that sense that makes a pine tree 

 grow straight upward. A plant that curves assumes that 

 position because its sense of gravitation makes it take the 

 one best suited to its needs. Some flower stalks are very 

 curiously guided by the gravitation sense. The narcissus 

 is an example. At first there is a straight shaft, pierc- 

 ing the ground with its compact pointed flower bud, but 

 as the flower opens, the stalk bends close to the top and 

 brings the flower tube into a roughly horizontal position, 

 where it shows off its bright colored crown to attract the 

 insects, on the visits of which it depends for fertilization, 

 the flowers are guided to the right position by the gravita- 

 tion sense, and they increase or diminish the angular bend 

 in their stalk until the right position is attained. 



