LABORATORY STUDIES 31 



forms a purplish or brown slimy layer on flower pots in 

 greenhouses. 



(6) For false tissues examine a longitudinal section of the 

 stalk of a toadstool. Here the longitudinal rows of cells are 

 distinct filaments grown together into one mass. Similarly 

 the basal portion of the apothecium of cup-fungi is made up of 

 false tissue, although here the separate filaments are often 

 indistinguishable. Some of the algae are also good examples, 

 e.g. Udotea, Lemanea, Nemalion, etc. 



(c) For meristem examine a thin longitudinal section of a 

 root tip. For this purpose the first strong root from a ger- 

 minating grain of Indian corn or the young, so-called "brace 

 roots" from near the base of the stem of that plant are good, as 

 are young roots from onion or hyacinth bulbs. By staining 

 lightly with eosin or safranin the nuclei and cytoplasm become 

 more distinct. 



(d) Make similar longitudinal sections of a very young flower- 

 or leaf-bud, e.g. lilac or elder, or of the growing tip of asparagus 

 or of a pumpkin or squash vine and examine the meristem tis- 

 sue. Compare the cells with those in corresponding locations 

 in sections made in the older parts of the stem. 



(e) For parenchyma cells make thin longitudinal and cross- 

 sections of a young green stem of Indian corn or of a green shoot 

 of elder. Excluding the woody and epidermal parts the bulk 

 of the stem at this stage consists of parenchyma. Treat the 

 section with iodine solution and then with sulphuric acid. A 

 blue coloration indicates cellulose. 



(/) Make a cross-section of a typical leaf such as apple, lily, 

 nasturtium, etc. The green cells are parenchyma tissue. 



(g) Make a thin section of the tuber of potato to show 

 storage parenchyma. Similar parenchyma may be found in 

 the fruit of an apple or pear, etc. 



(A) In thin cross or tangential sections of a living woody twig 

 will be found the medullary rays. These consist of rather thick- 

 walled living parenchyma, the walls being more or less lignified 

 and provided with thin spots (pits) here and there through 

 which water and food substances can pass from cell to cell. 

 Stain different sections with iodine and sulphuric acid as a test 

 for cellulose, and with a five percent aqueous solution of phlo- 

 roglucin and hydrochloric acid as a test for lignified cell walls, 

 the latter taking a red coloration. Examine in similar manner 



