NATURE STUDIES. 



smaller and harder seed-vessels, which were probably 

 green when young, and brown when ready to fall 

 upon the ground. But some of them happened to 

 show a tendency towards producing larger and juicier 

 fruits, and these were constantly favoured by the 

 unconscious friendliness of the neighbouring birds. 

 The colour and the sweetness would soon follow, as they 

 have followed a thousand times over in the develop- 

 ment of each separate edible fruit. A grape, in short, 

 viewed from the standpoint of the vine itself, is merely 

 a cunning device for ensuring the assistance of birds 

 or mammals in dispersing the little, nut-like seeds of 

 which man takes, as a rule, such scanty notice. 



GERMS OF DISEASE AND DEATH. 



BY DR. ANDREW WILSON, F.R.S.E. 



MOST readers have heard of the " Germ Theory," and 

 there are few persons who do not know what the 

 hypothesis of that name means and implies. Popularly 

 regarded, this theory holds that a very large proportion 

 of the diseases that affect and afflict man and his neigh- 

 bour animals, owe their origin to minute forms of life 

 whether animal or vegetable, or both, is still, in 

 most cases, a matter of doubt. To select a single 

 illustration of the application of this theory, we may 



