VARIATION IN DIFFERENT PORTIONS OF PLANT. 



41 



whorls to the total number borne by Ceratophyllum plants than do primary 

 branches. Also, one notes that the character of the distributions is 

 changing. While the most frequently occurring whorls on the second- 

 ary branches are, as in the case of the primaries, those having 9 leaves, 

 yet whorls with fewer than 9 leaves occur proportionately much more 

 frequently on secondary than on primary branches. We should expect, 

 then, that the average number of leaves to the whorl would be less 

 for the secondaries than for the primaries. That this is in fact the 

 case is shown in table 18. Series V and VI still maintain their peculiar 

 character. In Series V the actually most frequent whorls are those 

 having 7 leaves, though 8 and 9 leaved whorls are nearly as frequent. 

 Series VI has the greatest frequency at 10, as in the case of the pri- 

 maries. 



Table IS.— Constants for variation in leaf-number in whorls on secondary branches. 



We see in this case as before a close similarity between the results 

 for Series I, II, and III. Series V shows the highest variabilities for 

 this portion of the plant, and Series VI the highest means. Comparing 

 the results with those for primary branches, it appears that secondary- 

 branch whorls have fewer leaves to the whorl and are more variable 

 than those on primaries. The nature and the extent of the differences 



