STRONG DRINK AND TOBACCO SMOKE. 21 



Plate 3, fig. 1 7, represents a young barley plant about 

 six inclies liioh. A slis-bt swelling will be observed at one 



o o o 



jDart of it, g. When cut open vertically its whole length 

 (fig. 18), the stem is found to be perfectly hollow, except- 

 ing at certain points of it, where (as at a, h) diaphragms, 

 or solid plates of cellular tissue, extend across it. Just 

 above the upper one of these plates is a small, conical 

 semi-transparent body, g. Fig. 19 is a highly-magni- 

 fied representation of this part, which in reality is, at 

 this time, no bigger than the head of a pin. Observe 

 that all but the two inner leaves of the stem have 

 been removed to show it more clearly. This minute 

 body consists of two parts, and from it grow, by con- 

 stant addition of new tissues, the inflorescence or flower 

 axis, a (fig. 19), and h, the leaf axis or stem, the entire 

 mass forming the terminal bud of the plant of which a 

 and h are the flower and stem portions in a rudimentary 

 state. 



The mode of growth may be thus explained. Whilst 

 the base of the terminal bud rested as it were on the 

 diaphragm d, a leaf-bud was formed, and, on expanding 

 into a leaf, the tissues from which it grew on the stem 

 also increased and lengthened by the constantly renewed 

 vitality imparted to them by the respiration of the leaf. 

 By the time the stem has grown the length of the inter- 

 node (fig. 18, a to h), the terminal bud has also increased 

 in diameter, another leaf-bud is forming, and the phsnt 

 repeats the process of horizontal and vertical growth. 



At each point, where a new leaf-bud, and consequently 



