ADJUSTMENT OF ORGAXISMS TO ENVIRONMENT 403 



ceased to appear see figure 27, on page 35. The function of 

 these has been discussed pn page 34. 



Study these individually, and write their characters with 

 which we are now concerned in a table prepared with the 

 following column headings: 



Name. 



Sex (male, female or bisexual). 



Form of flower cluster. 



Number of stamens per flower. 



Number of pistils per flower. 



Number of pollen grains per stamen. 



Number of ovules per carpel. 



Ratio for the whole plant of pollen grains to ovules. 



The labor of making this table chiefly consists in counting 

 the pollen grains in anthers of the nine species selected. 

 The number of ovules will usually be found stated in the 

 larger works on systematic botany, and these may be used 

 for reference. Since there are some slight difficulties of 

 manipulation to be encountered, it may be well to suggest, 

 how to proceed. 



Get anthers for pollen counting from unopened buds, in 

 order that the previous shedding of some of the pollen may 

 not vitiate the count. Select anthers of average size, or, 

 better, count several and average the result. 



Large anthers, like those of trillium, should be divided, 

 say into eighths, and a part taken. This is easily done by 

 placing the anther flat on a slide and pressing the edge of a 

 scalpel into it with a rocking motion, being careful to make 

 approximately .equal successive divisions. Then select an 

 average segment, expose its pollen fully, cover and count, 

 and multiply to get the whole. Very small anthers, like 

 those of the dandelion, are likely to be quite transparent, 

 and need only to be mounted and covered, and their pollen 

 content may be counted at once. It will be necessary to 



