BLASTOGENIC VARIATIONS. 181 



bility, he refers to the stigmatic bands on the seed cap- 

 sules of Shirley poppies. These vary in number from 

 about 7 to 18, the most commonly occurring number 

 being 12. The variability of a large number of indi- 

 viduals (as expressed by the error of mean square), 

 which were taken as a good sample of the whole race, 

 was found to be 1.885. The average variability of the 

 bands in the capsules obtained from each of 300 differ- 

 ent plants, or the individual variability, was, however, 

 only 15 per cent. less. Again, with reference to the 

 number of leaflets on the compound leaf of the ash, the 

 individual variability was only 8 per cent, less than the 

 racial variability. 



In a recent paper,* Professor Pearson and his co- 

 workers have determined the relationship between 

 racial and individual variability in a number of other 

 plant species. Enumerations were made of the veins 

 in the leaf of the Spanish Chestnut and the Beech, of 

 the prickles on Holly leaves, the sori on the fronds of 

 Hartstongue ferns, the seeds in the pods of Broom 

 plants, etc., and measurements of the length and 

 breadth of ivy leaves and of the gills of mushrooms. 

 On an average, the individual variability was found to 

 be about 87 per cent, of the racial, it varying in the dif- 

 ferent series of observations between 77 and 98 per 

 cent. Now, even admitting that in these instances the 

 individual variability is only slightly smaller than the 

 racial, it does not appear to me that Professor Pearson is 

 entitled to his contention, for all these highly variable 

 individuals were, of course, produced as the result of 

 sexual union in their immediate or remote progenitors. 

 * Phil. Trans, 1901, A. p. 285. 



