Cleavers. 107 



ducing them, they had to set to work at once manu- 

 facturing new organic material for the further develop- 

 ment of the plant. Luckily they happened to 

 grow in a position where the sunlight could fall upon 

 them— a good many seedlings are more unfortunate, 

 and so starve to death at the very outset of their 

 careers — and by the aid of the light they immediately 

 began decomposing the carbonic acid of the air and 

 laying by starch for the use of the younger generation 

 of leaves. At the same time the vigorous young sap 

 carried these fresh materials of growth into the tiny 

 sprouting bud which lay between them, and rapidly 

 unfolded it into such a shoot as you see now before 

 you, with level whorls of quite differently shaped and 

 highly developed leaves, disposed in rows of six or 

 eight around the stem. 



Observe that the adult type of leaf appears here 

 suddenly and as it were by a leap. If we could 

 reconstruct the whole past history of the goose-grass, 

 we should doubtless find that each change in its 

 foliage took place very gradually, by a thousand 

 minute intermediate stages. Indeed, many of these 

 stages still survive for us among allied plants. But 

 the impulsive goose-grass itself clears the whole dis- 

 tance between the primitive ancestor and its own 

 advanced type at a single bound. The intermediate 



