Oct., 1923] STOUT STUDIES OF LYTHRUM SALICARIA 447 



mid-styled plant M no. I (see table 2). Of the 22 flowers on it that were 

 crossed during the first 18 days of bloom there were only two failures, 

 the highest number of seeds for a capsule being 176 and the average 98. 

 Whether such pollination would be more effective than selfing during the 

 last part of the period of bloom was not tested. 



Self-compatibility Tests by the Bagging Method 



A total of about 600 plants have been grown in pedigreed cultures from 

 seed. A considerable number of these have been tested for self -com- 

 patibility in the following manner: branches were enclosed in glassine paper 

 bags, and pollinations of flowers opening within were made from day to day. 

 Long-styled plants and short-styled plants were selfed by using the pollen 

 from mid-length stamens, and the mid-styled by use of the pollen of long 

 stamens. In making pollinations, stamens with dehiscing anthers were 

 removed with sterile tweezers and brushed on pistils, leaving an abundance 

 of pollen. In cases of pseudo-proterogyny the fully protruding pistils of 

 partially opened flowers were likewise treated along with pistils of more 

 mature flowers. It appears that in the decidedly pseudo-proterogynous 

 flowers the pistils protrude long before they are receptive to any kind of 

 fertilization, and that highest seed production in compatible fertilizations 

 occurs when pollination is made at or about the time that petals open and 

 pollen is shed. On plants two or more years old, a total of as many as 500 

 or more flowers were often thus pollinated. On plants in the first year of 

 growth from seed the number thus selfed was often much less. 



These tests are undoubtedly less adequate than tests in isolation for 

 revealing feeble grades of self-compatibility and in showing such changes in 

 self-compatibility as are seen in the plant M no. 1, but hand-pollinations 

 make certain that pollen in abundance is applied to the stigmas at the time 

 when they are judged to be most receptive. 



The general results summarized for each form without reference to 

 lines of descent are as follows: 



Fully Self- Feebly Self- Medium Self- Highly Self- 



incompatible compatible compatible compatible 



Mid-styled plants 64 20 21 



Long-styled plants 83 14 o 



Short-styled plants .... 22 1 o 



An attempt has been made to grade the plants according to whether the 

 self-compatibility is feeble, medium, or strong, the judgment being based on 

 the proportion of selfed flowers that gave pods and the number of seeds 

 produced. Results typical for various grades are given in table 1. The 

 tests made show that many plants of the species are without doubt entirely 

 self-incompatible (M 5-1 no. 13 in table 1 for example), and that others are 



