Harris, Observations ori the Physiology of Seed Development in Slaphylea. 15 



According'ly a difference of one node in the position of a fruit 

 would be accompauied by no niore change in the iiiean number of 

 seeds than 1/100 to 2/100 seeds. This aniount is so small that 

 with no more than two thousand fruits, one cannot even be sure 

 of the sign of the relationship. Diag-ram 1 shows by the slope 

 of the lines and the plotted empii'ical nieans, how insignillcant the 

 correlation is. 



The niean of the three reg'ression coefficients is only — .0035 

 while for the regression of oviües on position as found in another 

 place we have the average value — .0933. This result agrees with 

 the conclusion drawn from the individuals of the 1906 collection, 

 that the number of seeds developing is less dependent upon the 

 position of the fruit on the inflorescence axis than is the number 

 of ovules formed. I believe this result will be surprising to many 

 botanists. 



The same thing is made very clear by combining the three 

 series of material and determining the coefficients of fecundity for 

 the first five nodes of the inflorescences. We have: 



Position on rr j. 1 /-> ^ i rp , 1 o 1 I Coefficicnt 

 T a iotalUvules iotai oeeds ; r. -r?. li. 



innorescence i oi recundity 



1 



97420 



10224 



.1049 



2 



66504 



6817 



.1025 



3 



23224 



2469 1 



.1063 



4 



i 3094 



345 i 



.1115 



5 



i 334 



35 j 



.1048 



V. Summary and conclusions. 



1. The foregoing pages contain the tabulated data and the 

 results of analysis for three series coniprising altogether over eight 

 thousand fruits of Staphylea irifolia. The purpose of the work is 

 to ascertain something concerning the internal factors influencing 

 the development of the seed. 



2. Much dogmatism prevails among biologists concerning the 

 "explanation" of "fluctuating variability". It is freqiiently assumed 

 that any Variation polygon based upon ''pure" material may be at 

 once interpreted in terms of external environmental influences and 

 internal differentiation. 



3. Where an individual produces a series of organs which 

 differ among themselves, it is generally assumed by biologists that 

 differences in the vigor of individual branches or those due to 

 "periodicity" will largely account for the "partial variability" 

 observed. In some cases these factors probably have a considerable 

 influence on the determination of the characters of the organs of 

 an individual, but in the present material, the relative as well as 

 the actual number of seeds developing seems to be very little 



