LABORATORY STUDIES AND DEMONSTRATIONS. 213 



If time presses, the detailed study of microscopical sections 

 may be omitted, but a series of prepared sections should be kept 

 on hand and a demonstration given. 



The embryological development is too difficult to study, but 

 very instructive demonstrations may be given by those who have 

 had some experience. In the neighborhood of Philadelphia egg- 

 capsules may be found in great numbers in old manure-heaps, 

 in May and June. One end of the capsule should be sliced off 

 with a very sharp scalpel and the contents drawn out, under 

 water, with a large-mouthed pipette. The mass may then be 

 mounted in water under a supported cover-glass and studied 

 with the microscope. The embryos may be preserved in 

 Perenyrs fluid, and either studied whole in the preserving fluid 

 or hardened in alcohol and cut into series of sections. 



CHAPTERS IX TO XI. (THE COMMON BRAKE.) 



Except when the ground is frozen Pteris may be dug up and 

 brought into the laboratory in a fresh state. Fronds may be 



~ f V 



cut and dried in midsummer and considerably freshened (bv a 



t/ \ t/ 



moment's immersion in warm water) when needed to be used (in 

 the opening exercise) to illustrate the aerial portion of the plant. 

 Hhizomes may be obtained at convenience and kept in weak 

 alcohol (50$). 



The Morphology of the Body. To illustrate this, one whole 

 and entire plant should, if possible, be at hand for examination. 

 The aerial and the underground portions may then be sketched 

 in their normal relations. Branches, roots, and old leaf-stalks 

 should be pointed out, identified, and sketched. 



The Anatomy of the Rhizome should first be made out with 

 the naked eve. The lateral ridges will be detected bv the class, 



I/O v 



which should be asked to draw the cross-section as seen with 

 the naked eye. For this preliminary work each student should 

 have a piece of rhizome two or three inches in length. (Care 

 should afterwards be taken that the drawing has been correctly 

 placed dorsoventrally.) A rough dissection with jack-knife or 

 large scalpel may next follow, with inferences as to the characters 

 of the several tissues found (as fibrous, pulpy, woody, etc.). 



The ^licroscopiG Anatomy of the Rhizome is interesting, and, 



