Trifolium pratense.—­One hundred flower-heads on plants protected by a net did not produce a single seed, whilst 100 heads on plants growing outside, which were visited by bees, yielded 68 grains weight of seeds; and as eighty seeds weighed two grains, the 100 heads must have yielded 2720 seeds.  I have often watched this plant, and have never seen hive-bees sucking the flowers, except from the outside through holes bitten by humble-bees, or deep down between the flowers, as if in search of some secretion from the calyx, almost in the same manner as described by Mr. Farrer, in the case of Coronilla (’Nature’ 1874 July 2 page 169).  I must, however, except one occasion, when an adjoining field of sainfoin (Hedysarum onobrychis) had just been cut down, and when the bees seemed driven to desperation.  On this occasion most of the flowers of the clover were somewhat withered, and contained an extraordinary quantity of nectar, which the bees were able to suck.  An experienced apiarian, Mr. Miner, says that in the United States hive-bees never suck the red clover; and Mr. R. Colgate informs me that he has observed the same fact in New Zealand after the introduction of the hive-bee into that island.  On the other hand, H. Muller (’Befruchtung’ page 224) has often seen hive-bees visiting this plant in Germany, for the sake both of pollen and nectar, which latter they obtained by breaking apart the petals.  It is at least certain that humble-bees are the chief fertilisers of the common red clover.

Trifolium incarnatum.—­The flower-heads containing ripe seeds, on some covered and uncovered plants, appeared equally fine, but this was a false appearance; 60 heads on the latter yielded 349 grains weight of seeds, whereas 60 on the covered-up plants yielded only 63 grains, and many of the seeds in the latter lot were poor and aborted.  Therefore the flowers which were visited by bees produced between five and six times as many seeds as those which were protected.  The covered-up plants not having been much exhausted by seed-bearing, bore a second considerable crop of flower-stems, whilst the exposed plants did not do so.

Cytisus laburnum (Leguminosae).—­Seven flower-racemes ready to expand were enclosed in a large bag made of net, and they did not seem in the least injured by this treatment.  Only three of them produced any pods, each a single one; and these three pods contained one, four, and five seeds.  So that only a single pod from the seven racemes included a fair complement of seeds.

Cuphea purpurea (Lythraceae).—­Produced no seeds.  Other flowers on the same plant artificially fertilised under the net yielded seeds.

Vinca major (Apocynaceae).—­Is generally quite sterile, but sometimes sets seeds when artificially cross-fertilised:  see my notice ‘Gardeners’ Chronicle’ 1861 page 552.

Vinca rosea.—­Behaves in the same manner as the last species:  ‘Gardeners’ Chronicle’ 1861 page 699, 736, 831.