130 Principles of Plant Culture. 
An unnatural curling of the leaves, with yellow spots and 
small wart-like excrescences on their surface, are some of 
the symptoms of this trouble. Less water, inereased light 
and reduced bottom heat furnish the remedy. 
224. Water-Sprouts (sap-sprouts, gormands) on fruit 
trees are sometimes due to an excess of water in the soil. 
These thick, rapidly-growing shoots, with remote leaves and 
poorly-developed buds, growing from the main branches of 
unthrifty fruit trees, are most common on undrained, heavy 
soils. They rarely produce much fruit, but tend to rob the 
bearing branches of light and nourishment. They usually 
continue growth late, and in severe winters are often injured 
by cold. Water-sprouts may also result from over-pruning 
and from injury of the tree by cold, but in the absence of 
these conditions, they suggest the need of drainage. 
225. Fruits and Vegetables often Crack from Exces= 
sive Moisture, either through increased absorption by the 
roots, or by direct absorption through the skin. Cracking 
is most frequent after heavy rains following drought. Ap- 
ples, tomatoes, melons, carrots, kohl-rabi and the potato 
tuber are subject to it. On wet soils, draining may largely 
remedy the evil. The selection of varieties least subject to 
it is also helpful, especially in melons and tomatoes which 
often crack in comparatively dry weather. In these cases, 
the cracking is probably due to an unequal maturing of the 
fruit which causes certain parts to grow faster than others. 
226. Knobby Potatoes are caused by a wet period, 
following a drought, during the ripening season. Parts of 
the plant that are still alive, stimulated by abundant water, 
resume growth. But since cell division is possible only in 
the parts containing protoplasm, the mature cells of the 
