224 JOURNAL OF THE EOYAL HORTICULTURAL SOCIETY. 



Insecticides {Bev. Hort. Beige, January 1901). — The followin<r 

 receipts are recommended against crickets and cockroaches : — (i.) Borax, 

 2 parts ; flour, 1 part, (ii.) Borax, 2 parts ; powder oi Pyrethrum, 2 

 parts ; flour, 1 part, (iii.) Borax, 2 parts ; powder of Pyrethrum, 2 parts ; 

 powder of Colocynth, 1 part ; flour, 1 part. — G. H. 



Ipomoeas, Japanese. By Wilhehn Miihle, junr. {Die Gart. 22, 

 p. 260).— Coloured fig. of fourteen vars., and fig. of twenty-five forms of 

 leaves in outline. — .4. H. K. 



Iris Tauri. By G. B. Mallett {Gard. Chron. p. 190; fig. 74; 

 23/3/1901).— Description and figure.— CV. S. S. 



Iris Tubergeniana. By G. B. Mallett {Gard. Chron. p. 190 ; 

 23/3/1901).— Described. -6^. S. S. 



Iris Willmotiana. By M. Foster {Gard. Chron. p. 261 ; fig. 100 ; 

 27/4/1901). — A new species introduced from Eastern Turkestan in 1890. 

 Described and figured. — G. S. S. 



Irrig-ation, Prog-ress in the Study of {Bull. Bot. Dej). Jam. 

 Jan. 1901, p. 2). — Apart from the drier western, even the more eastern 

 and humid regions of U.S. are benefited by irrigation ; for the rainfall 

 in Wisconsin does not supply sufficient moisture for maximum crops, the 

 profit from irrigation on Corn* being ^2.16 per acre, and for Potatos ^11.70, 

 &c. Irrigation should not be excessive, as the fertilising materials may be 

 washed away. M. Edmond Gain found that " at the time of planting 

 the soil should have about 25 per cent, of the total amount of watei- 

 which it is capable of holding, then it should fall to 15 per cent., and 

 remain at this point until the first leaves are formed, when it should be 

 raised quickly to nearly 40 per cent. It should be allowed to fall rapidly 

 to about 25 per cent., and remain at this point until shortly before flower- 

 ing, when it may be raised gradually to 40 per cent, and then allowed to 

 fall rapidly to 12 or 15 per cent., where it remains during fruiting and 

 maturity." These ideal conditions of alternate dry and wet periods 

 should be aimed at, if they cannot be actually secured, as it is the best 

 method of keeping the soluble constituents of the soil near the surface. 

 On "akali" soils, however, under the above conditions the corrosive 

 poisonous alkaline salts w^ould accumulate at the surface, to the destruc- 

 tion or great injury of the crop.t 



Sub-irrigation on a large scale by drain-pipes is not so effective as 

 surface irrigation by furrows in increasing the yield of field crops ; but 

 for garden crops, e.g. Celery, &c., drain pipes first laid ujwn the soil 

 parallel with the young plants, and then covered as the rows are banked, 

 proved very efficacious, the water being poured in at one end, the other 

 being, of course, blocked. — G. H. 



Ivy as a Border Plant {Bev. Hart. Beige, February 1901).— Is 

 recommended by M. J. Burvenich. — G. H. 



* Presumably Indian Corn or Maize. 



t This is specially dealt with in the March number, p. 86. 



