Every farmer knows the familiar and destructive fungus known as “rust of wheat,” it is one of a large class of most interesting plants. The “rusts” are interesting to the microscopist on account of their structure and to the botanist because they cannot, like other fungi, complete their lives upon one plant. They derive their popular name from the fact that they look like patches of rust upon the plants on which they live. Some of the greatest living agricultural botanists have spent many years on producing races of wheat upon which rust fungus will not grow. Wonderful success has rewarded their efforts and conferred immense benefits upon farmers. In spite of this, however, we need not despair that we shall be unable to find a specimen for our microscope, though it is happily an undoubted fact that the disease is not so common now as a few years ago. [Illustration: _Photos by Flatters & Garnett_ 1. CLUSTER CUPS The spring stage of Rust of Wheat. Little orange cup-shaped growths on the under side of a Barberry leaf. They germinate on Wheat to form the summer stage of “Rust.” 2. RUST OF WHEAT These little stalked spires are the winter stage of a serious disease of Wheat. In the spring they germinate on Barberry. 3. POLLEN GRAINS ON A GRASS FLOWER The feathery stigmas of grass flowers are beautifully adapted for catching and holding pollen grains. 4. THE LOWER SIDE OF A FERN FROND One of the brown outgrowths on the under side of a fern frond. The stalked spore cases are seen, protected by an umbrella shaped covering. ]