POLLINATION OF THE BRITISH PRIMULAS. 129 
Eusphalerum primule, abundant, but less frequently and more locally ; 
Various other minute beetles ; 
Teniothrips primule, frequent in the corolla-tubes *, 
VT.— Critical Remarks on the Observations. 
In view of the foregoing, the casual critic may well ask :—Are not the 
visits of all these numerous insects amply sufficient to ensure the adequate 
pollination of the flowers of all our three Primulas? At first sight, one 
would certainly conclude that they are; but, the more one looks into the 
matter, the more one comes to see that they are not. 
In examining in detail the evidence in support of this statement, it will be 
found convenient to work backwards, considering in the reverse order the 
four groups of insect visitors already described. 
Of the small insects included in Group 4, by far the most important is the 
minute beetle, Meligethes picipes, which is quite obviously incapable of 
pollinating the flowers of either form in the regular and orthodox manner. 
Yet there seems every probability that it is quite capable of pollinating (in 
fact, actually does pollinate, though irregularly) the flowers of all our three 
Primulas to a considerable extent, not only illegitimately, but also even 
legitimately—as effectively, in fact, as this could be done by any long- 
tongued insect inserting its proboscis and sucking the nectar in the regular 
and orthodox manner f. 
Take the case of one of these beetles alighting upon (say) a long-styled 
flower. At once it enters the corolla-tube, squeezing past the stigma, upon 
which it leaves inevitably some of the pollen with which it is dusted (some 
of which will have come, almost certainly, from some short-styled flower 
previously visited) ; then, descending the tube to the nectaries, it squeezes 
past the anthers, dusting itself with more long-styled pollen ; next, returning 
upwards, it again squeezes past the anthers, dusting itself with more long- 
styled pollen; finally, it flies away to another plant, which we may assume 
to be short-styled (for it is as likely to be that as not). Entering the corolla- 
tube, the beetle squeezes between the anthers, dusting itself freely with 
short-styled pollen ; descends the tube, squeezing past the stigma, on which 
it will inevitably leave some of the pollen brought from the long-styled 
flower previously visited; next it reaches the nectaries ; returning, after 
feeding, it again squeezes past the stigma, on which it leaves more pollen ; 
finally, after squeezing again between the anthers, it again flies away to 
* See ante, p. 123. 
t That the beetle is capable of doing this has been held by others, including 
Prof. F. E. Weiss (see Nature Notes, xv. p. 106) and E. T. Daubeny (see Nature Notes, 
xvi. p. 116). 
LINN, JOURN,—BOTANY, VOL, XLVI. K 
