21 



that in the cross-fertilisation experiments it was noticed that the 

 seedless hops in the control bunches were attacked by mould to a 

 much greater extent than the seed hops on the same bine. Accord- 

 ingly a large number of half-seedless hops were examined to see 

 whether the mould did more damage on the seedless part than on 

 the seeded portion. This was found to be the case. The seedless 

 portions were usually completely destroyed, while the fertile portions 

 grew out almost normally (Fig. 5). Further, in hops which con- 

 tained only one or two fertile bracteoles it was constantly seen that 

 these structures were hardly affected, while the rest of the hop was 

 destroyed (3-5, Fig. 5). 



The above experiments and observations all point to the 

 necessity of fertilisation in the production of well-grown hops of the 

 desired colour. On the other hand, the absence of fertilisation leads to 

 small, green, unripe hops, particularly liable to total destruction by 

 mould. As is well known, it is during the burr stage that hops are most 

 liable to damage by mould. This seems, apart from climatic con- 

 siderations, due to two main causes. In the first place, the feathery 

 stigmas arrest the mould spores as they blow past, and also tend to 

 keep the atmosphere around the spores moist and so assist in their 

 germination. Secondly, unless pollination takes place as soon as the 

 stigmas are receptive, there seems to be a pause in development, 

 during which the hop waits for the process to take place. It would 

 appear, therefore, that any arrest of growth at this period is particu- 

 larly dangerous, and everything should be done to rapidly carry the 

 young hops through this critical phase. 



It seems difficult, therefore, to escape the conclusion that, under 

 the conditions obtaining in Kent, the growth of seed hops rather than 

 seedless hops should be aimed at. Before, however, any special 

 recommendations are made on such an important subject as this, it 

 is proposed to carry out further investigations during the coming 

 summer on the lines indicated below. The present paper is put 

 forward merely as a contribution to the subject. 



The advantages of growing seed hops seem to be the following : 

 i. Large, heavy, brightly- coloured and well-grown-out 

 specimens. 



