CXC PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



Clubbing in Cabbages. — Mr. Massee pointed out that if the seed-bed 

 is well dressed with lime, and the seedling plants get over the first three 

 weeks of their life free from attack, there is comparatively little danger of 

 subsequent infection. 



Chlorosis of Apple and other Trees. — In reference to this subject, 

 discussed at the last meeting, Mr. Gaut now sent twigs of Apple trees 

 and of Raspberries from a garden in Yorkshire, together with samples of 

 the soil taken at a depth of nine inches and of eighteen inches respec- 

 tively. It was suggested that the samples be sent to the analyst to 

 determine whether or no they contain copper. 



Pollination in Orchards. — Mr. F. J. Chittenden, F.R.H.S., sent the 

 following communication : — It has been frequently noticed that in large 

 plantations of one particular variety of Apple or Pear the quantity of 

 fruit produced greatly diminishes from the outside of the plantation 

 towards its centre, and the explanation apparently is that foreign pollen — 

 that is, pollen from another variety of Apple or Pear, as the case may be — 

 is necessary for the proper fertilisation of the ovules, in order that fruit 

 may be set at all. It seems also that incomplete fertilisation may also 

 take place, owing possibly to weakness in the pollen of the particular 

 variety, resulting in the formation of misshapen or malformed fruit. 



The fertilisation of the ovules depends chiefly upon three factors : — 



1. The occurrence of suitable, weather conditions at the time of the 

 receptivity of the stigma and the ripening of the pollen. 



2. In the case of self-sterile varieties, the presence of bees or other 

 insects to carry pollen from one flower to another. Muller gives a list of 

 nine bees visiting flowers of Apple (Bombus Hortorum, L. ? being 

 especially abundant), as well as other insects (seven) visiting the flower 

 for honey or pollen : and a list of six bees (Apis mellifica, L. $ very 

 abundant), as well as twenty-four other insects visiting the flowers of Pear 

 (Fert. of Floivers, pp. 238, 239). He also says that if bees fail to visit 

 the flowers, self-fertilisation occurs in each case, but he is presumably 

 speaking of the wild plants, Pyrus Mains, L., and P. communis, L., and 

 not of garden varieties. 



3. In the case of the self-sterile varieties, the presence of plants in 

 the near neighbourhood whose pollen will fertilise the ovules of the self- 

 sterile variety. 



This last factor is the one most under the control of the grower, and 

 therefore the one upon which definite knowledge is essential, and though 

 much has been done in America in finding out which are the self-sterile 

 varieties, &c, very few definite experiments, carried out on lines which 

 admit of a minimum of error in the result, appear to have been conducted, 

 or at least recorded, in this country. American results are not altogether 

 reliable here, owing (1) to the difference in the varieties grown, and (2) 

 the difference in the meteorological conditions. 



In an attempt made quite recently to ascertain which varieties of 

 Pears were self-sterile, and therefore not suitable for large plantings by 

 themselves, I tested the following fifteen varieties : — ' Bellissime d'Hiver,' 

 ' Beurre* d'Amanlis,' 1 Beurre Superfin,' 'Catillac,' 'Conference,' 'Doyenne 

 du Cornice,' ' Durondeau,' 'Easter Beurre,' 'Emile d'Heyst,' 'Jargonelle,' 

 ' Josephine de Malines,' ' Louise Bonne of Jersey,' ' Pitmaston Duchess,' 



