1 Jan., 1898. ] QUEENSLAND AGRICULTURAL JOURNAL. 31 
fertilisation, be the form of procedure that is habitual with its blossoms; and 
if the latter, and this be accomplished by bees, whether it be of the two the 
process that is followed by the better of the results attainable. 
That oranges may be self-fertile has been affirmed by G. Gallesio,* as we 
learn from ©. Darwin (op. cit., p. 894). Moreover, Dr. O. Penzig reports that 
the method of fertilisation by self-impollination sometimes oceurs as shown by | 
the researches of Prof. Delpino; this investigator having enclosed flowers and 
so secured them against the visitations of insects, with the result, notwith- 
standing, that some fruit set ;t but he also argues, that in the case of the flowers 
of the orange their large size, their structure, their conspicuous colouration, 
their odour, and their abundance of nectar point to the fact that cross-fertili- 
sation that is effected by insects is the form of fertilisation that almost always 
transpires. Without doubt, he writes (to render his statement in the English 
vernacular), the method of impollination that takes place in the orange is cross- 
fertilisation. He also informs.us that in Italy—and the same is true with 
regard to that which occurs in Queensland—the common bee especially, but also 
alarge number of other Hymenoptera of medium stature, seek with avidity the 
nectar distilled from the dise of the flower, and transport the pollen from 
flower to flower (O. Penzig, 1c.) 
Thus, whereas natural crossing and crossing effected through the agency 
of insects—and especially bees—may both take place in the case of the orange, 
there are grounds for concluding that the Jatter is that which usually occurs. 
It is, moreover, probable that the benefits derived therefrom are in excess of 
those resulting from spontaneous crossing. In the case of this spontaneous 
process, it may be assumed that it more frequently happens than otherwise 
that the pollen or fecundating agent is derived from flowers close at hand—as, 
for instance, from adjacent branches of the same tree—than it does that this 
comes from the flowers of trees of a different horticultural variety than is 
represented by the one supporting the flowers under observation, or of such as 
18 growing under different conditions than those that are found to obtain in its 
case. Now it has been experimentally shown by the late Charles Darwin 
“that the mere act of crossing by itself does no good, but that 
the advantages thus derived depend on the plants which are crossed, 
either consisting of distinct varieties which will almost certainly differ 
somewhat in constitution, or on the progenitor of the plants which are 
crossed, though identical in every external character, having been subjected to 
somewhat different conditions, and having thus acquired some slight difference 
in their constitution.”{ This necessary condition for successful crossing has 
been found to be especially true in the case of the pear. M. B. Waite has 
shown that self-pollinated fruits, using the term as before explained (vid. Note 
p. 80), may be readily distinguished from cross-pollinated ones, even when 
growing side by side on the tree, by difference of size, amongst other distin- 
guishing characters that are in favour of those fruits that have originated from 
the latter process. On the subject of this enhanced size, he writes: ‘‘In the 
self-pollinated there was a tendency to be smaller. Their average size was less, 
although many individuals compared favourably with the crosses. ‘The largest 
fruits, however, were always crosses. . . . Aself-pollinated fruit, favourably 
situated, may grow to be larger than a cross on the same tree less favoured, 
while on the other hand a cross under the same conditions would exceed the 
the self-pollinated pear. Cross-pollination may be regarded, with vegetative 
vigour of the tree, as one of the factors in the production of fine fruits.”§ 
The same able investigator also remarks (p. 73) that ‘the tendency of the 
self-pollinated fruits is to be narrower, and not well filled out at the blossom 
end.” Self and cross pollinated fruits, when hanging side by side upon the 
LD 
* Probably in his ‘‘Traité du Citrus,” Paris, 1811. 
+ O. Penzig : ‘Stud. Botanici sugli Agrumi,” &c., p, 65, Rome, 1887. 
+, Darwin, op. cit., p. 297. Of. also zb., chap. vii. I 
§ M. B. Waite, op. cit., p. 74. ° 
