CHap. X. PLANTS STERILE WITHOUT INSECT- AID. 361 



Lotus corniculatus (Leguminosse). Several covered-up plants 

 produced only two empty pods, and not a single good seed. 



Trifolium repens (Leguminosse). Several plants were protected 

 from insects, and the seeds from ten flower-heads on these 

 plants, and from ten heads on other plants growing outside 

 the net (which I saw visited by bees), were counted ; and 

 the seeds from the latter plants were very nearly ten times 

 as numerous as those from the protected plants. The ex- 

 periment was repeated on the following year; and twenty 

 protected heads now yielded only a single aborted seed, 

 whilst twenty heads on the plants outside the net (which I 

 saw visited by bees) yielded 2290 seeds, as calculated by 

 weighing all the seed, and counting the number in a weight 

 of two grains. 



T. j)ratense. 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 

 G8 grains weight of seeds ; and as eighty seeds weighed two 

 grains, the 100 heads must have yielded 2,720 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, p. 169). I must, how- 

 ever, except one occasion, when an adjoining field of sainfoin 

 (Hedysarurn 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 contain*! 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. E. 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. Midler (' Befruchtung,' p. 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. 



T. incarnatum. The flower-heads containing ripe seeds, on some 

 covered and uncovered plants, appeared equally fine, but 



