NATURE NOTES 237 



food, (3) poisoning from gases of the air (in cities) and harmful 

 substances in soil ( e. g., excess of common salt), (4) wounds allow- 

 ing entrance of injurious organisms, especially fungi, (5) loss of 

 necessary parts (e. g., leaves and roots destroyed by insects), (6) 

 fungi, the most fruitful cause of disease (e. g., blotches on fruits and 

 leaves, rotting of plants internally and externally). It is this last 

 class of plant diseases which requires medicinal treatment — most 

 commonly by chemicals sprayed over affected parts. 



Flowers which do not open. A recent paper (reviewed in July 

 /'/(/;// World) by the German botanist Goebel, cites facts which lead 

 to the conclusion that cleistogamous flowers are due to insufficient 

 nutrition, and not caused by the lack of pollinating agencies, as has 

 been commonlv supposed. In other words, such flowers as the closed 

 gentian originally failed to " grow open " because of insufficient suit- 

 able food and not as a response to a demand for special adaptation 

 made necessary because insects for pollination were wanting. 



City People in the Country. According to the passenger agents of 

 several of the great railroad systems centering in New York, the 

 present season has witnessed an unprecedented exodus to the country 

 for the summer, particularly of people of moderate means. And an 

 especially gratifying feature of this exodus, noted by these same 

 agents, is the largely-increased number of people who are either 

 buying or renting small houses surrounded by a few acres of land for 

 gardening and light farming. One agent declares that the demand 

 for these small plots along his line, convenient to the city, is far in 

 excess of the supply. " They all want a house with a garden," said 

 one of these men, " and the bigger the garden, the better it suits." 

 How much more sensible and conducive to the comfort, pleasure and 

 health of a family is a vacation spent on one of these small farms 

 than in the ordinary country hotel or boarding-house need hardly be 

 said. And where the distance from the city and other conditions are 

 such as to permit a man of family to make his permanent home in one 

 of these rural localities, where he may have a bit of ground to till 

 in his leisure hours and days, the arrangement is still happier and 

 more advantageous all around. — Leslie's Weekly. 



Why our Common Weeds are Introduced Species. The fact that 

 practically all the weeds seen growing in vacant lots, along roadsides, 

 in cultivated and uncultivated fields in Canada and the United States, 

 are introduced species, is known to botanists; but the reason why 

 these introduced plants should become weeds and our own should 

 not, is not so generally known or thought of. At a meeting of the 

 Botanical Branch of the Ottawa Field-Naturalists' Club held last win- 

 ter. Professor John Macoun explained the matter to everyone's satis- 

 faction. Ontario and other parts of Canada were heavily wooded 

 before the settler came and the native plants grew in the woods, along 



