RELATIVE SIZE OF DIFFERENT DIVISIONS OF PLANT. 



51 



(6) Of the remaining whorls usually somewhat more are borne on 

 secondary branches than on the main stem. This of course only applies 

 to plants which have secondary branches. Taking all the plants together 

 as they stand in the table, the weighted mean percentage contribution 

 of the main stem to the total number of whorls is 14.1 per cent. Reck- 

 oned in the same way the mean percentage contribution of the secondary 

 branches is 27.0 per cent, or very nearly twice that of the main stem. 



(c) Tertiary and quaternary branches contribute, on the whole, a 

 very small proportion of the total number of whorls. Calculating the 

 mean percentage contribution from table 25, I find that it is 3.3 per cent 

 for tertiary branches. 



Table 27. — Frequency distributions for size of secondary branches. 



The plants of Series IV differ in their percentage constitution very 

 distinctly from the others, in the direction of having a lower proportion 

 of main-stem whorls, and a higher proportion of secondary-branch 

 whorls. The most striking exception in the table is afforded by plant 

 1 of Series VI, in which there are 14 per cent more whorls on secondary 

 than on primary branches. But this is a small plant and clearly the 

 probable errors of the percentages are high. As a matter of fact this 

 plant had only three primary branches, while there were eight secondaries 

 and one tertiary. It is not surprising, since the plant as a whole was so 

 small, that the eight secondary branches should contribute a larger 

 number of whorls to the total than the three primaries. 



I wish to call attention at this point to a matter which otherwise 

 might be overlooked. If the values given in table 25 be studied in con- 

 nection with the constants given in table 2, it will be seen that there is 



