124 Botanical Microtechnique 



week to 10 days after emergence, the seedling has leafy axillary buds 

 (Fig. 13.3a). The tassel primordia become evident 25 to 30 days 

 after emergence (Fig. \S.S b) . Instructive vegetative and floral 

 apices can be obtained from the sprouts that arise from sods or 

 clumps of the larger perennial grasses, such as brome grass or orchard 

 grass. Inflorescences are initiated during April (Fig. 13.3 c) , and 

 vegetative tips are obtainable from the new sprouts that emerge in 

 midsummer or later. Excellent preservation of these gramineous 

 growing points can be obtained with Craf I. The air must be com- 

 pletely evacuated from the tightly overlapping leaves encircling the 

 stem tip. Improper infiltration results in the collapse of the meriste- 

 matic tissues and breaking of the tip and leaf primordia during 

 sectioning. Cut sections of maize 10 to 12 [i thick and Avena 6 to 8 ^. 

 Stain in tannic acid-ferric chloride, in hemalum-safranin, or in 

 safranin-fast green. 





r -3 



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Fir.. 13.1-Mcthods ot ohiiiiniiii; apitiil mcristcms. A, seedling of coin, growing 

 |)()ini of sum is at coleoplile node I, root tip removed from seminal root 2; /J, half 

 of kidniv iK'an seed witii embryo in place; C. parts of embryo. 1 contains stem tip, 

 2 is discarded, 3 is used for root tip: D. sprouting pea, epicotyl cut off at 1 is used 

 for stem tii), root tip (ui olf at 2; /•; and /•'. s|)routing soybean dissected to obtain 

 terminal bud (,: H J. I)ud of basswood removed from twig and divided for killing. 



