CHAP. XI. PERFORATION OF THE COROLLA. 431 



He gathered in Switzerland 100 flower-stems of the 

 common blue variety of the monkshood (Aconitum 

 napellus), and not a single flower was perforated ; he 

 then gathered 100 stems of a white variety growing 

 close by, and every one of the open flowers had been 

 perforated. This surprising difference in the state of 

 the flowers may be attributed with much probability 

 to the blue variety being distasteful to bees, from the 

 presence of the acrid matter which is so general in the 

 Kanunculacese, and to its absence in the white variety 

 in correlation with the loss of the blue tint. Accord- 

 ing to Sprengel,* this plant is strongly proterandrous ; 

 it would therefore be more or less sterile unless bees 

 carried pollen from the younger to the older flowers. 

 Consequently the white variety, the flowers of which 

 were always bitten instead of being properly entered 

 by the bees, would fail to yield the full number 

 of seeds and would be a comparatively rare plant, 

 as Dr. Ogle informs me was the case. 



Bees show much skill in their manner of working, 

 for they always make their holes from the outside 

 close to the spot where the nectar lies hidden within 

 the corolla. All the flowers in a large bed of Stachys 

 coccinea had either one or two slits made on the upper 

 side of the corolla near the base. The flowers of a 

 Mirabilis and of Salvia coceinea were perforated in the 

 same manner ; whilst those of Salvia grahami, in which 

 the calyx is much elongated, had both the calyx and the 

 corolla invariably perforated. The flowers of Pentstemon 

 argutm are broader than those of the plants just named, 

 and two holes alongside each other had here always 

 been made just above the calyx. In these several cases 

 the perforations were on the upper side, but in Antir- 



* Dae Entdecke,' &c. p. 278. 



