MAIZE STEM 95 



VEGETATIVE ORGANS. (B) MONOCOTYLEDONS 



i. STEM HERBACEOUS TYPE 



Fruits of Maize should be sown in pans, in spring, and kept 

 in a cool house or frame : they may be bedded out in early 

 summer, and the plants will be suitable for the observations 

 detailed below in August. Fresh material may be used, but 

 stems preserved in alcohol are preferable. 



I. Cut transverse sections from about the middle of an 

 internode of a well-grown stem of Zea Mais : mount in water, 

 or glycerine. The sections should be cut from the upper part 

 of one of the lower internodes, otherwise the vascular bundles 

 may be found to be imperfectly developed. 



Examine with a low power, and, beginning the study of the 

 tissues at the periphery of the section, observe 



a. A single layer of rather irregular epidermis : immediately 

 below this are 



b. Irregular groups of sclerenchyma with thick lignified 

 walls : internally lies 



c. A mass of parenchyma, which forms the ground-work of 

 the whole section : embedded in this are 



d. Numerous vascular bundles : note that they are smaller, 

 but more numerous near the periphery than at the centre ; also 

 that the position of the parts of the bundles relatively to the 

 centre of the section is usually uniform. 



Treat a section with chlor-zinc-iodine : put on a high power, 

 and examine in detail the several tissues above named. 



a. The epidermis appears as a definite layer of cells of un- 

 equal size, without intercellular spaces. Note a well-marked 



