PRACTICAL WORK. NO. XIII. 223 



ii. Cut transverse sections of open flowers of Galtha 

 palustris (Marsh Marigold) and wash off the sections of 

 carpels from the razor into a watch-glass of water. 

 Mount in dilute glycerine a section which contains ovules. 

 Shew in your sketch, under a low power : 



a. the carpel with its midrib ; 



b. the ovule or ovules, attached by stalks (fu nicies) 

 to the margins of the carpel. Note that the ovules are 

 anatropous ; 



c. the embryo-sac. 



Sketch the contents of the embryo-sac under high 

 power, shewing 



d. the egg apparatus, consisting of two synergidse and 

 an egg-cell; 



e. the antipodal cells ; 



f. the secondary nucleus of the embryo-sac. 



iii. Examine the fruits of Capsella (Shepherd's purse) 

 and pull off the ovary wall from some of the youngest. 

 Numerous ovules spring from the margins of a central 

 dividing wall. Remove with needles some of the ovules 

 to a watch-glass containing a little potash solution, and 

 after soaking for five or ten minutes (until they are 

 almost transparent) mount them in a drop of glycerine or 

 water on a slide, giving one gentle but sudden tap to the 

 coverslip to burst the ovule and force out the embryo. 

 In this way various stages in the development of the 

 embryo may be obtained, and should be carefully sketched. 

 Use a high power for very early stages, and a low power 

 when the cotyledons can be easily identified. 



