126 MR. MILLER CHRISTY ON THE 
to a distance (in some species) of as much as 3 or 4mm. This is especially 
the case with flowers of the short-styled form, the “throat” (or entrance to 
the corolla-tube) of which is expanded to a depth of from 3-4 mm. This 
(being about equal to the difference in depth between the tubes of the two 
forms) places the two forms very much on an equality so far as the visits of 
bees are concerned. 
V.—Summary of Observations on Insect Visitors. 
The observations, by myself and others, set forth in Section II, prove 
beyond dispute that all our three species of Primula are visited not uncom- 
monly, during the day, by a fair number of different species of insects, some 
of which are sufficiently long-tongued to be capable of pollinating their 
flowers effectively. - 
At first sight, it might seem that this fact alone, once definitely established, 
ought to suffice to solve the whole problem. Unfortunately, it will be found 
that this is, for several reasons, very far from being the case, One must, 
therefore, consider in detail how the foregoing observations bear upon the 
problem. For this purpose, it is necessary to summarise them; and this is 
attempted in the following paragraphs, 
The observations in question show that about fifty-five species of insect and 
other small creatures have been recorded as visiting or frequenting the 
flowers of our three species of Primula, namely :— 
Arachnida ............,.,,,.... 2 species. 
Coleoptera ..........,......... 20 species (about). 
Diptera ....:......,.....,.... 5 species (about). 
Hymenoptera ...:............... 16 species (about). 
Hemiptera :.............,..... l species. 
Lepidoptera .................. 6 species. 
Orthoptera ........,.,,..,... 1 species, 
Thysanoptera .........,.....,.. l species, 
Isopoda ,...........,......... 2 species. 
Gastropoda ......,.,..,,........ 3 species (about). 
Total ................ 57 species (about). 
Of these species, however, at least one-third may be disregarded, inasmuch 
as they are not “visitors” in the true sense, but robbers, which frequent the 
flowers, mainly at night, with the object of feeding on either nectar, or 
pollen, or the actual substance of the corolla. These may be disregarded for 
present purposes ; for, if they effect pollination at all, it is by chance merely 
and certainly to a negligible extent only. No one can regard them as having 
been intended by nature (so to speak) to effect regularly and normally the 
pollination of the flowers. 
