LEAVES AND BUDS. 139 



173. Brussels Sprout. To get a good idea of bud- 

 structure, first examine some Brussels Sprouts. 



(1) Pick off the leaves one by one, starting from the 

 outside, and note that each leaf has a small bud in its axil. 

 How do the inner leaves differ (in size, form, texture, colour) 

 from the outer ones ? How may these differences be accounted 

 for? 



(2) Slice down through the middle of another sprout, and 

 notice the conical end of the stem, with small outgrowths at 

 its extreme tip; these outgrowths are the youngest leaves. 

 Below these are older leaves, gradually becoming distinctly 

 divided into blade and stalk ; lower still come leaves whose 

 blade is folded between the veins. In the axil of each leaf is 

 a small bud, resembling a miniature sprout ; some of these 

 buds may be cut through in the slice (if not, make more 

 slices). Notice the strings (veins or vascular bundles) in 

 the stem of the Sprout. Sketch a good clear longitudina 1 

 section, at least the natural size. 



(3) Cut a series of cross sections, beginning at the top of 

 the Sprout and proceeding to the base ; lay the sections out 

 in order, then compare and sketch them. 



(4) Set a Sprout with its cut end in red ink, and after a 

 time cut slices and notice the bundles which extend nearly to 

 the extreme tip of the stem and give off branches to the leaves 

 and buds. 



(5) Remove most of the larger outer leaves, and notice 

 that the inner ones soon become wilted if the sprout is set in 

 a dry place. 



(6) Weigh (a) an entire sprout, (6) one from which all the 

 large outer leaves (which overlap and protect the young inner 

 ones) have been removed ; set both in a dry place, and in a 

 few hours, or a day, weigh again and compare the loss in 

 weight in the two cases. 



Lettuces and Cabbages may be used in addition to Sprouts. 

 Why are the inner leaves softer and lighter-coloured than the 

 outer leaves ? What other differences do they show ? 



174. Winter-Buds (Resting-Buds). In cold climates 

 the buds formed at the close of the year do not develop at 

 once, but remain dormant after the leaves have fallen. When 

 a resting-bud is about to be formed, the last foliage-leaves on 



