Ch. IV 



GROWTH OF PLANTS 



161 



products of respiration, both carbon dioxide and lieat are 

 released in growth. 



All of the iDhenomena here described in connection -nith 

 stems appear also in leaves, roots, and other parts, as shown 

 by use of a suitably 

 modified auxograph. or 

 by the measuring mi- 

 croscope. .111 parts are 

 found to exhibit the 

 grand period, and the 

 fluctuations in relation 

 to the weather ; and 

 the only appreciable 

 differences in their 

 modes of groT^-th are 

 associated v,ith their 

 cUfferences in construc- 

 tion. Stems grow liy 

 the progressive elonga- 



FiG. 113. — The place of expansion in 

 jrroT^-th of a typical leaf of English Ivy, as 

 shoTm by the spread of the marks e^'eIlly 

 made on the small leaf at the right : X t. 



tion of their internodes, which, forming in the bud, go 

 through their grand periods in succession : and thus is pro- 

 duced the famihar appearance 

 which has been compared with 

 the opening out of the joints of a 

 telescope (Fig. 112 >. The leaves, 

 quite difi'erently, expand pretty 

 eA'enly throughout their structure 

 (Fig. 113), going each through its 

 grand period, as do flowers and 

 fruits. The roots, on the other 

 hand, grow almost solely near 

 their tips (Fig. 114 >. their indi- 

 T-, , ,. ^-idual cells passing verv quieklv 



Fig. 11-4. — The place ol i- ^ . i . 



elongation in gromh of a typ- through the grand period, on 

 ical root of Corn, as shown by ^^.^^^^-^ account roots seem as a 



the spread ol evenJv spaced 



marks; X i- whole to gTOw eveiilv. This 



