742 Botanical Microtechnique 



well be processed with tertiary butyl alcohol, and any age classes that 

 cannot be cut in paraflin must be cut unembedded or in celloidin. 



Flax root has a simple diarch stele. Roots can be obtained easily by 

 germinating seeds in blotting paper. Radish, mustard, cabbage, and 

 many other roots also may be grown in this manner to adequate size 

 for primary tissues and processed by the methods given for apple. 



Ranuncidiis root has long been popular as an example of the dicot 

 root. The large fleshy roots of the buttercups, R. septe^itrionalis and 

 R. fascicularis, are easy to obtain and to process, using the methods 

 given for apple. The buttercup root is less likely to be of interest to 

 the student than the roots of economic plants. 



Large taproots like those of alfalfa, Medicago, and sweet clover, 

 Melilotus, are handled like the older semiwoody roots of apple. 



The tough, woody stems, rhizomes, and roots of ferns, horsetails 

 and club mosses are most con\ eniently discussed at this point because 

 they are handled like other woody materials. Collect the rhizomes of 

 ferns in the spring, just after the fronds ha\e fidly expanded. 

 Acceptable preservation of rhizomes can be obtained with FAA, and 

 it is not improbable that for investigational work this formula could 

 be adjusted to give good fixation with given species. For routine 

 preparation of many species, uniformly good results have been 

 obtained with Graf II. The subjects become very brittle after xylene, 

 but very large rhizomes can be cut readily after 7?-butyl or tertiary 

 butyl alcohols. It has been customary to embed hard rhizomes like 

 those of Pteris aquHina in celloidin. However, the TBA process is 

 satisfactory for portions of the rhizome that are not excessively hard, 

 but have the woody structures adequately lignified to show the 

 mature condition of tissues. The most brilliant and satisfactory stain 

 is safranin with fast green. The presence of yellow deposits in the cells 

 prodiues undesirable staining effects with the hematoxylins. 



The fleshy root of Botrychium is recommended. 1 csts with B. 

 virginianum have shown iliai (.lal 1 gives much better fixation than 

 does FAA. A very striking color contrast is obtained with safranin-fast 

 green. Roots of the Boston fern and of available native ferns are 

 processed as above. 



Species of Lycopodium occur in a])undance in some regions, and 

 some species, especially troj)ical ones, are culti\ated in conservatories. 

 Stems may be fixed in FAA and carried through tertiary butyl alcohol 

 to paraffin. It is usually necessary to soak the nu)unied specimen in 

 warm water before sectioning. Roots are easy to process successfully 

 by the same methods. 



