Page:Insectivorous Plants, Darwin, 1899.djvu/36

 were compared by number, weight, and measurement, with the following striking results : -

These results show clearly enough that insectivorous plants derive great advantage from animal food. It is of interest to note that the most striking difference between the two sets of plants is seen in what relates to reproduction-i. e. in the flower-stems, the capsules, and the seeds.

After cutting off the flower-stems, three sets of plants were allowed to rest throughout the winter, in order to test (by a comparison of spring-growth) the amounts of reserve material accumulated during the summer. Both starved and fed plants were kept without food until April 3rd, when it was found that the average weights per plant were 100 for the starved, 213.0 for the fed. This proves that the fed plants had laid by a far greater store of reserve material in spite of having produced nearly four times as much seed.

In Kellermann and Von Raumer's experiments (loc. cit.) aphides were used as food instead of meat-a method which adds greatly to the value of their results. Their conclusions are similar to my own, and they show that not only is the seed production of the fed plants greater, but they also form much heavier winter-buds than the starved plants.

Dr. M. Büsgen has more recently published an interesting paper" on the same subject. His experiments have the ad- vantage of having been made on young Droseras grown from seed. The unfed plants are thus much more effectually starved than in experiments on full-grown plants possessing already a store of reserve matter. It is therefore not to be wondered at that Büsgen's results are more striking than Kellermann's and Von Raumer's or my own-thus, for instance, he found that the "fed" plants, as compared with the starved