664 
THE QARDENINU WORLD. 
August 20, i.904. 
to which form the flower belongs, for the relative position of 
the stigma to the anthers indicates it at once. 
If during the season that the Primrose is in flower one 
were to note how many pint-eyed or thrum-eyed plants were 
growing in a certain area, or to pick them as they came, the 
probable result is (and others have made the same observa¬ 
tion) that neither form, would greatly predominate. 
This remarkable feature (dimorphism) greatly interested 
Darwin, and he set to' work to find out for what purpose Nature 
had] adopted this contrivance. After 1 long and careful expert 
ments the great naturalist came to the following conclusions, 
that “the flowers had been rendered heterostyled toi ensure 
crosst-fertilisatiom,” and that “ the complete fertility of flowers 
is only obtained! (that isi, a full yield of fertile seed) when 
pollen is taken from lonig stamen to long style, or from, short 
stamen to short style, which, of course, involves cross-feirtilisa- 
tion. In the last journal of the R.H.S. (May, 1904, p. 697) 
reference .is made to an article on “ The Fertilisation of the 
Primrose,” in which the writer differs from Darwin, and 
endeavours to show with much force that the short-styled or 
“ thrum-eyed ” variety is, at any rate., self-fertilised, and points 
out that both forms are rarely visited by insects with a 
sufficiently long proboscis. The reason for stating that the 
“ thrum-eyed ” variety is self-fertilised is as follows: That 
the anthers, which are directly over the pistil, burst when 
mature, and then curve inwards to the centre of the corolla 
tube, thereby closing up- the corolla tube, and so preventing 
any foreign pollen tot pass from the outside into the corolla 
tube containing the short style. Moreover, the anthers open 
on their inner and under surface, shedding their pollen so 
as to fall on the stigma immediately below. 
It is quite impossible for the wind to convey pollen from 
the short- anthers to the short pistil; therefore if Darwin’s 
theory on this point is correct, the pollen must be conveyed 
by insects, 'this being a very doubtful point. 
Such are the views that the field naturalist holdsi concerning 
the fertilisation of the Primrose, as opposed to the exp-eri- 
mentalislt’s views. 
Some months: ago I had under my charge a batch of a 
special strain of Primula oboonica, and it was my duty, being 
in a. large nursery, to obtain as much seed as possible from 
this batch. Previous experience had taught me that these 
Primula® would not. seed freely enough unless they were hand 
pollinated. I was naturally much perplexed, not knowing 
which way to set about pollinating, and being much interested 
in this question, I decided to experiment, for myself. For 
this purpose I selected 200 plants, upon which I experimented 
as follows: — 
No. of Ovaries 
Plants. Results. fertilised. 
1 ... 50 ... Pin-eyed x thrum-eyed ... Good yield of seed ... 75-80% 
2 ... 50 ... Thrum-eyed x pin-eyed ... „ „ ... 70% 
3 ... 10 ... Pin-eyed x pin-eyed ... ... No seed whatever ... — 
4 ... 10 ... Thrum-eyed x thrum-eyed ... Poor yield ._ ... 10% 
5 ..20 _ Thrum-eyed, self-pollinated ... No seed whatever ... — 
6 . 20 ... Pin-eyed ,, ... Poor yield.5-10% 
7 . . 40 ... Regardlessly pollinated ... Fair yield . 35-40% 
So very decided are the results of my experiments in 
Darwin’s favour that were it not for these experiments, I 
would not venture toi write upon such a scientific problem. 
I hope to have more to say upon this subject in a later 
rssnifl Herbert Cowley. 
Another Century Plant.—A writer on Yucca gloriosa 
(Adam’s Needle) describes it a.s a rare tropical plant in full 
bloom in the Adam and Eve Gardens, Seaharn Harbour, New- 
castle-on-Tyne. Going further, he states that it blooms once in 
50 years in its own country, and in any other region once in 100 
years. He is thus very precise, and we should like to know 
where he got his wonderful information. It must be a severe 
tax upon the plant to know when its flowering period is due, and 
whether it is at home or abroad. Should he chance to stray 
into Adam and Eve’s Gardens next year he may find the erratic 
plants flowering again if there are any strong crowns that have 
not bloomed upon them at the present time. We should like to 
hear his explanation of such an occurrence. 
Two Campanulas. 
As- in the cultivation of other plants, so in the instance of 
the Campanulas, much of the success arrived at is probablv 
due more to the: attention paid to later details, such as in 
watering, than to the primary processes through which thev 
pass. J 
The two' species to be dealt with are worthy of much observa¬ 
tion ; these are Campanula pyramidalis and C. isophylla. Re- 
gaiding the former, its splendour is- unblemished at any time, 
even in deformity ! Its stateliness at the present moment de 
serves more'than, slight approbation. Seed should be sown in 
the greenhouse during February; and at the: moment of writ¬ 
ing (August) the seedlings should be in 8-in. or 6-in pots • 
which sizes should contain the stability of upholding the 
necessary supply of nourishment required during the winter 
months. 
Much importance is attached to, the maintaining of a diy 
atmosphere during the short days: as C. pyramidalis is easily 
“ damped ” at that period. 
Early in, the following April 'they will require a shift into 
8-in. and 9-in. pots, in which they will subsequently be 
flowered in August—ra, very appropriate time for them to come 
in. After potting, they may then b© placed in the open air on 
a bed of ashe-s and grown on the same principle as early- 
flowering pot Chrysanthemums. Removing them into the 
greenhouse when the spikes are 2 ft. or 3 ft. long is beneficial 
to fiee and clean opening of the flowers. The plants may be 
grown on for several years:, when they attain enormous dimen¬ 
sions, and are indeed magnificent. The variety alba is a pure 
white, and oompaota, a pretty deep blue. 
Campanula, isophylla is a suitable supplement to- C. pyra- 
midalis. As- a trailer attaining a length of 2 ft. or 3 ft., it is 
befitting, either for edging the greenhouse stages or for liang- 
ing baskets. In the latter mode the variety alba, is grown to 
perfection -by Mr. Clark at Rannerfield, Selkirk. Both the 
blue and the white: varieties a,re -exceedingly beautiful. The 
shape of the fl-ower is very similar t-o> pyramidalis, though 
somewhat smaller in, size, and -having the petals more rounded. 
Propagation by cuttings in. the spring is the best means of 
multiplication. 
The plants may be grown on a, second or third year; but, 
-any longer is not advisable, since, after that period, the flowers 
degenerate extensively in -size. 
Tlie considerable: value of both species as conservatory 
flowers is best known to: those who: are fortunate enough to 
employ them in that manner. Those who do- not possess them 
are unfortunate indeed. For pot culture they are pre-eminent, 
in the distinctive! sphere of plants to: which they belong—the 
hardy and half-hardy. ’ James P. Dickson. 
New Stock for Rambler Roses. 
The: stock now most commonly employed for Rose® in this 
country is the D-og Rose, so called, which is a very composite 
lot, and may not always be confined to Rosa, can-ina, and it® 
immediate allies. The- Manett-i is generally advocated for 
pot work, while the Dei la Grifferaie is usually employed for 
climbing Roses of the Rosa multiflora type and others. The 
Dutch, have discovered that Rosa rugosa makes an excellent 
stock for Crimson Rambler, grown in the form of standards:, 
and this- finding is corroborated by a correspondent of “ The 
Flou istsf Exchange. The system is- to insert cuttings of Rosa 
rugosa, in the open ground, lo-ng and strong shoot® being 
employed. After being grown for o-ne season they are headed 
down to- the ground 1 the following spring. A strong shoot or 
several may be produced, but the best, o-nly is retained, -and 
it is fit for budding some time during the same season. 
Crimson Rambler budded on. this stock will give several shoots 
4 ft. long the first, season. Besides making strong growth, 
Rosa rugosia, raised 1 from cuttings, produces plenty of roots, 
and otherwise seems- to: fulfil the requirements of a good stock. 
Judging from the vigour of the plants worked upon this 
Japanese Rose, it. will prove a very durable stock. 
