138 ELEMENTS OP BOTANY. 



, Pull ofE a sepal and make a sketch of it, natural size ; then remove a 

 petal, flatten it out, and sketch it, natural size. 



' Observe that the flower-stalk is enlarged slightly at the upper end into 

 a rounded portion, the receptacle, from which all the parts of the flower 

 spring. 



Note how the six stamens arise from the receptacle, three of ^ them 

 from points just within and above the origins of the petals, the other 

 three from points between the petals. Remove the remaining petals 

 (cutting them off near the bottom with a knife), and sketch the stamens, 

 together with another object, the pistil, which stands in the centre. 



Cut off one stamen, and sketch it as seen through the magnifying glass. 

 Notice that it consists of a greenish stalk, the filament, and a broader 

 portion, the anther. Fig. 116, B. The latter is easily seen to contain a 

 prolongation of the green filament, nearly surrounded by a yellow sub- 

 stance. In the bud it will be found that the anther consists of two long 

 pouches or anther-cells, which are attached by their whole length to the 

 filament, and face inward (towards the centre of the flower). When the 

 flower is fairly open, the anther-cells have already split down their 

 margins, and are discharging a yellow, somewhat sticky powder, the 

 pollen. 



Examine oie of the anthers with the microscope, using the two-inch 

 objective (No. 1), and sketch it. 



Cut away all the stamens, and sketch the pistil. It consists of a stout 

 lower portion, the ovary, which is six-ridged or angled, and which bears 

 at its summit three slender stigmas. 



In another flower, which has begun to 'Either (and in which tSe ovary 

 is larger than in a newly-opened flower), cut the ovary across about the 

 middle, and try to make out with the magnifying glass the number of 

 chambers or cells which it contains. Examine the cross-section with the 

 two-inch objective ; sketch it, and note particularly the appearance and 

 mode of attachment of the undeveloped seeds or ovules with which it is 

 filled. Make a vertical section of another rather mature ovary, and 

 examine this in the same way. 



Using a fresh flower, construct a diagram to show the relation of t^e 

 parts on an imaginary cross-section, as illustrated in Fig. 135.^ Con- 

 struct a diagram of a longitudinal section of the flower, on the general 

 plan of those in Fig. 133, but showing the contents of the ovary. 



1 It is important to notice that sucli a diagrain is not a picture of the section 

 actually produced by cutting through the flower crosswise at any one level, hut that 

 it is rather a projectwn of the sections through the most typical part of each of the 

 floral organs. 



