SUaOKST/OXS FOR LAIHUtATttRV WoliK. 



(>:< 



position in the cell, 

 (e) The threads of protoplasm connecting the nucleus 

 with the lining of the cell. 

 Having observed these features in the living specimen try the 

 effect of introducing a drop of iodine solution under the 

 cover-glass. "What is the effect upon the cell-wall ? 

 Upon the green spirals? Upon the nucleus? Try also 

 the effect (ujiou freshly mounted specimens) of a weak 

 (2^ per cent.) solution of common salt; of glycerine; of 

 weak solution of potash. 

 All these observations may be repeated with any other simple 

 vegetable forms, such as the prothallium of a fern, where 

 the cells form a surface instead of a thread as in Spirogyra. 

 i'lie movements of protoplasm may be easily observed in tlie 

 root-hairs of aquatic plants, and in the stamen-hairs of 

 Tradescantia. 



THE BEAN AND THE MAIZE. 



For practical work on the Bean and the Maize, seeds of these 

 plants should be germinated in wet sawdust and the 

 roots allowed to attain a length of several inches. "Well- 

 grown plants should also be availal)le. 



Root of Bean. 



Make cross-sections of the primary root a little back of the 

 apex ; clear in weak potash, and mount in glycerine. 

 Note the following in order from the centre : 



(a) Tlie Pith, occupying the centre of the section, 



(b) Several (usually four) groups of primary xylem 



elements. 



(c) Alternate with, and somewhat exterior to tlii-se, 



the phloem groups. 



(d) Filling the spaces between all the groups of 00 



and (c). parenchymatous tissue. 



(e) External to the xylem nn<l phloem groups, a 



rather well marked l)elt of pericambium in a 

 single layer, at least in tiiat i.ortion wlr. h is 

 outside the phloem. 



(f) External to the pericambium, a well marked 

 single layer of cells, each with a characteristic 

 dark dot on its radial walls. This layer consti- 

 tutes the btmdle-sheath {rmlotUnnis). 



(g) External to ( f ). a thick ban.l of many layers of 



cells, the cortex ; and finally. 



