402 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



by cultivators, who pointed to some kinds of insectivorous plants 

 growing and flourishing apparently without any insect food, and 

 who doubted whether any advantage accrued to these plants 

 from the absorption of nitrogenous matter. This is the weak 

 point in Charles Darwin's work — no attempt was made to prove 

 experimentally the amount of benefit accruing to the plants 

 by nitrogenous food. His son, Francis Darwin, however, has 

 proved conclusively, in the case of Drosera rotundifolia, that 

 insect-fed plants bear heavier and more numerous seeds than 

 unfed ones. The experiments were conducted with great care, 

 all likely sources of fallacy having been avoided. He grew two 

 lots of plants under similar conditions ; one lot he fed with roast 

 meat, one-fiftieth of a grain being placed on the secreting glands, 

 while from the other all such material was carefully excluded. 

 The results were most marked in the number and weight of the 

 seeds. The number of seeds produced by the fed plants was as 

 240 to 100 of the unfed ones, while the total weight of the seeds 

 was as 380 to 100. The number and weight of the flower-stalks 

 and seed-capsules were also greatly in favour of the fed plants. 

 After the flower-stalks had been removed, the plants were 

 allowed to rest in a greenhouse during winter. On being 

 examined in spring, it was found that the fed plants had laid 

 up a much larger store of material than the unfed ones, for the 

 total weight of plants was in the proportion of 251 to 100 of the 

 unfed plants, and the average weight of each plant was as 213 

 to 100. While Darwin was performing these most interesting 

 experiments, Drs. Kellerman and Eaumer were, all unknown to 

 him, prosecuting almost identical inquiries, and reaching almost 

 exactly similar conclusions. 



My own experience in the culture of Dionaea is, that when 

 two sets of plants are grown side by side under the same 

 conditions in every respect, except that insects are excluded from 

 the one and admitted to the other, the latter, or fed plants, are 

 found to be stronger and far superior to the former during the 

 following season. But we must never forget that the natural 

 conditions under which these plants are found are different from 

 what they are under cultivation. In their native habitats they 

 grow in very poor soil and make feeble roots, and under these 

 conditions may require to capture more insects by their leaves to 

 make up for their root deficiency. Under culture, however, fairly 



