266 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
ON THE USE OF TRANSPARENT PARCHMENT PAPER BAGS 
FOR ARTIFICIAL FERTILISATION. 
By Professor Huco pr Vries, Amsterdam University. 
SincE the year 1893 I have used for my experiments in artificial 
fertilisation in the open air caps and bags made of transparent parchment 
paper, such as are used largely in commerce for fruit and Grape 
culture. 
When it is desired to conduct experiments in selection with artificial 
pollination this must be effected in gardens, and therefore in the open 
air, because prior to the selection it is not known from which individuals 
the seed will have to be gathered; and after the selection it is, as a rule, 
too late to transplant the seed-bearers in order to transfer them indoors 
or into greenhouses. I therefore do all my fertilisation in the open. 
In order, therefore, to protect the flowers concerned from insects’ 
visits, | cover them with bags, which, according to my experience, are 
rarely damaged ; and both in sunny weather, as well as in wet and windy, 
keep in excellent condition. 
In wine culture, both on the Rhine and the Moselle, as well as else- 
where, these bags are used for the purpose of protecting the Grapes 
during their growth from wasps, vermin, and birds, fostering their growth 
and improving the quality. 
They are made of thin transparent parchment paper, saturated with 
some fatty substance, which prevents the passage of moisture, but permits 
that of light and sunshine. There is developed in these glass-like covers 
a greater and more lasting warmth, which consequently helps the growth 
of the fruits and Grapes, and presumably increases their sugar contents. 
Shortly after the flowering, when the berries and fruit have set, the 
caps and bags are placed over them, folded above around the fruit stalk, 
and bound either with a metallic clip or with string. They last for 
several years. 
These parchment paper bags are made in the bag factory of Mr. P. J. 
Schmitz, in Diisseldorf, of any required size. For fertilisation of 
Papaver somniferum 1 use, for instance, bags measuring 15 x 20 centi- 
metres. or covering the flower stems of Ginothera Lamarckiana I 
need bags 20 x 40 cm., or even larger. 
They are also made with perforations which afford more air, and on 
account of the smallness of the holes might also be used in fertilising 
work, though I have made no experiments with them so far. 
My experience with these bags is fairly extensive. With Papaver 
somniferum I have for five years used such covers for some fifty to 100 
flowers each year, fertilising partly with own pollen and partly with 
foreign pollen. With Q/nothera Lamarckiana and related species and 
varieties | have used annually some hundreds—in 1898, indeed, about 600 
individuals were covered. Furthermore, with the aid of such bags I have 
artificially fertilised Antirrhinum majus, Chelidonium majus, Linaria 
