Spermatophytes Angiosperms 



265 



is sufficient rigidity. Resort to pith only when necessary. In 

 cutting sections of a leaf like that of Lilium, lay one leaf on another 

 until you have a bundle of them which will be nearly square in trans- 

 verse section. Wrap the bundle with string for about 15mm.; cut 

 the bundle transversely so that about 5 mm. of the bundle will 

 project beyond the tied portion. Fasten the tied portion in the 



FIG. 93. Sparganium eurycarpum: photomicrograph of transverse section of young 

 root; fixed in chromo-acetic acid and stained in Bismarck brown; Cramer contrast plate; 

 16 mm. objective; ocular X4; no Abbe condenser; yellowish-green filter; camera bel- 

 lows, 1 meter; exposure, 8 seconds. X90. 



microtome, or hold it in your fingers, and cut transverse sections. 

 About 15 to 20 fj, is a good thickness for general leaf structure. 

 The sections of leaves in the center of such a bundle are likely 

 to be better than you could cut from single leaves held in pith. 

 In case of large leaves, cut out strips about 1 cm. square and tie 

 them together. 



Buds will furnish beautiful preparations of young leaves and, at 

 the same time, will show the vernation. Cut the bud transversely, 



