181 



Studies have been based on three dwarf varieties, Navy, 

 Golden Wax and Burpee's Stringless.* It has been shown that 

 the number of ovules laid down has a negligible influence upon 

 seed weight. The weight of the seed decreases as the number 

 of seeds per pod increases. The weight of the seeds also decreases 

 as the percentage of the ovules which develop into seeds becomes 

 larger. The biometrician expresses these results on a universally 

 applicable correlation scale, ranging from — i through o to + i. 

 Since — i would indicate a perfect negative correlation between 

 number of seeds per pod and seed weight, the average value 

 — .096 shows a very low relationship indeed. That for the 

 relative number of seeds developed is even lower, measured by 

 an average correlation coefficient of only — .075. 



In beans, the chance of an ovule developing into a seed in- 

 creases from the stem to the stigmatic end of the pod. Seed 

 weight is also influenced by the distance from the base of the 

 pod at which the seed is inserted. The twenty coefficients 

 which have been worked out for groups of pods with various 

 numbers of ovules range from + .078 to + .238. Thus from 

 the base to the tip of the pods seed weight increases slightly. 

 The rate of increase in seed weight seems in some cases to be 

 sensibly uniform, but in others weight increases rapidly at first, 

 then the rate of increase falls off, and finally the seeds become 

 somewhat lighter at the stigmatic end of the pod. 



In connection with Professor Halsted's suggestion concerning 

 the desirability of investigating the problem of fertility and seed 

 weight in wild plants, it is worth while to refer to results published 

 in an earlier number of ToRREYA.f 



In StapJiylea there is little difference between the average 

 weight of the seeds in pods with i and 2 seeds per pod, but when 

 more than these numbers develop the weight of the seeds is 

 sensibly lowered. 



* Harris, J. Arthur. A quantitative study of the factors influencing the weight 

 of the bean seed. I. Intra-ovarial correlations. Beih. Bot. Centralbl. Abt. I, 

 31: 1-12. pi. 1-4, 1913. See also J. Arthur Harris, The influences of position in 

 the pod upon the weight of the bean seed. Amer. Nat. 49: 44-47. fig. 1-3. 1915. 



t Harris, J. Arthur. Seed weight in Staphylea and Cladostris. Torreya ii: 

 165-169. 1911. 



