34 BOTANICAL GAZETTE | JULY 
Echium, but under Vicia Cracca this species is indicated as collect- 
ing pollen. In the Berlin garden Loew found it collecting pollen 
of Nepeta Mussint. In the two latter cases there is some error, of | 
the bee is not oligotropic. So of the cases mentioned by Lub- — 
bock, only one is exclusive, and two are not even oligotropic. 
Andrena cettu: females collect pollen of Scabiosa arvensis, 
Bombus gerstaeckeri: why Knuth says this species visits exclu- 
sively Aconitum lycoctonum 1 do not know, for on page 191 itis 
distinctly stated that the males and workers visit A. Napellus, but 
nothing is said about pollen-collecting. 
Osmia cementaria: males and females suck and collect pollen 
on Echium vulgare; males suck on Trifolium arvense. | 
Of the cases mentioned by Knuth, excepting Andrena nasuity 
only two are exclusive. Osmia aduncaand Bombus gerstaeckeri att 
not good cases. In the other cases the females collect the pollen : 
exclusively from the plants set opposite them, and the cases aft 
not essentially modified by occasional visits for nectar to othet 
flowers. I hold that Macropis labiata is as good a case as Andrent — 
florea. 
Of the cases mentioned by Loew, three have been passed 
upon. I know of nothing against any of them except Andreni 
cmneraria. The female collects pollen of Salix, but also of Za 
axacum officinale, so 1 should exclude it. 
In the observation of the insect visits of flowers correc 
determinations are very important, for otherwise the records are 
wrong. One has to be sure that the bee is actually collecting — 
pollen, for often a female bee will suck nectar from a flowet 
when her scopz are full of pollen from another species. On i 7 
other hand, there is danger of assuming that a bee is oligotropi ) 
from too few observations. 
A neighborhood where the flora and insect fauna are in thei 
normal condition is more favorable for correct observatiom | 
Yes eh ee 7 for, when the flowers upon which a eo | 
forebd (a Sait dowets hich oeioiy ict 
most cases the f a _— originally it did not visit. “4 
ormer is more likely to happen. 
Pe es ee gee 
