1 62 Experimental Zoology 



never appearing on the same plant. The long-styled, as its 

 name implies, has a long style reaching to the top of the corolla ; 

 the corolla is larger, the stigma globular, the papillae longer, 

 and the pollen grains larger than those in the short-styled 

 form. This long-styled form flowers first, on an average, but 

 the short-style averages more seeds. The stamens are in the 

 middle of the tube in the long-style form, and at the top of the 

 tube in the short-style form. 



Darwin carried out a series of important experiments on these 

 plants. He calls illegitimate unions those in which long-styled 

 flowers are fertilized by pollen from the same flower or from a 

 similar flower of the same or of a different plant. Similarly 

 for the short-styled form : legitimate unions are those between 

 long-styled and short-styled flowers. 



The behavior of the offspring from seeds of legitimate and ille- 

 gitimate unions is most surprising. In one case * an illegitimate 

 union between short-styled forms produced seeds that germinated 

 so badly that only 14 plants were obtained, of which 9 were short- 

 styled and 5 long-styled. 



In another experiment the stigma of a long-styled flower was 

 fertilized by the pollen of a long-styled flower. Three long- 

 styled plants resulted . From these, in turn, self -fertilized , 5 3 long- 

 styled offspring were obtained; from their seed 4 long-styled 

 plants; from their seed 20 long-styled; and from their seed 8 

 long- styled and 2 short- styled. 



In another plant, Lythrum salicaria, 3 forms occur: the 

 long-styled, the mid-style, and the short-styled type. The sta- 

 mens also occur under the same three lengths. Figure 1 7 shows 

 the conditions of the three kinds of flowers. 



There are 6 possible legitimate unions and 12 illegitimate 

 ones. To test these two kinds of unions, legitimate and 

 illegitimate, 18 distinct kinds of crosses must be made. 

 The results of these experiments are shown in the following 

 table :- 



1 " Different Forms of Flowers," p. 217. 



