THE CANADIAN H0BTI0ULTDBI8T. 



257 



ing the extreme heat of the day it 

 stands in the shade. I have planted 

 it for years on the same piece of land, a 

 heavy clay loam, well manured. 



Yours truly, Wm. KoUGH. 



(Srienttfo. 



PLANT LOUSE ON SPRUCE. 



Sir, — By referring to page 1 25 (June 

 Number) of the current volume it will 

 be seen that I received from Mr. John 

 Sailles some spruce twigs which seemed 

 to be effected by some parasite. Being 

 desirous of ascertaining the true nature 

 of the trouble, I sent the specimens to 

 Prof. Comstock, of Cornell University, 

 who replied that the twigs had been in- 

 fested with some insect that had then 

 passed into the pupa state, and that 

 when the imago appeared he would re- 

 port thereon. I wrote to Mr. Sailles 

 and obtained some fresh twigs, which 

 were also sent to Prof. Comstock, who 

 has favored me with the following reply. 

 Your obedient servant, 



D. W. Beadle. 



St. Catharines, Oct. 11, 1886. 



My Dear Mr. Beadle, — Your let- 

 ter of the 9th inst. was received during 

 my absence from Ithaca. This morning 

 is the first chance I have had to study 

 the plant louse on spruce. I think it 

 is Adelges ahieticoleiis. But there is no 

 good description of this species. See 

 Packard's Guide, tig. 520 (p. 523), and 

 Bulletin No. 7 of the United States 

 Entomological Commission, p. 234. 



As to remedies, try solution of soap, 

 quarter pound to one gallon of water. 

 It would be well to try the kerosene 

 emulsions recommended by Riley in 

 his re])orts. But be careful in the ap- 

 plication of these, lest the kerosene 

 injure the trees. 



Very sincerely yours, 



J. H. Comstock. 



Ithaca, N. ¥., 22nd Sept., 1886. 

 2 



THE RUSSIAN MULBERRY. 



Dear Sir, — I herewith enclose you 

 two leaves of the Jlussian Mulberry, 

 which are taken from trees growing on 

 my grounds. This variety is dioecious. 

 The leaves are cordate, one, you will 

 observe, is only serrated, which is the 

 female, or pistillate, tree beaiing fruit ; 

 the lobed, or oak-leaved, is from the 

 male or staujinate tree, blossoming pro- 

 fusely, but not fruit-bearing. 



Seedlings, therefore, planted singly 

 cannot be relied on. 



Of course, the practised eye of the 

 botanist will soon detect this. 



I am, yours truly, 



Simon Roy. 

 Berlin, 22nd Sept., 1886. 



IRON FILINCxS ABOUT PEAR TREES. 



Sir, — Regarding the use of iron 

 filings in promoting the fruitfulness of 

 pear trees, I would hesitate to give all 

 the credit to their use in the case re- 

 ferred to. The presence of iron is 

 necessary to the production of chloro- 

 phyll, one of the most important com- 

 pounds in the leaf. 



This is the chief agent at work in the 

 decomposition of carbonic acid, an im- 

 portant source of food for plants, by 

 su))plying carbon which enters largely 

 into their structure. The green color 

 of leaves is owing to the presence of 

 chlorophyll. Plants that grow in soil 

 containing no iron do not become green, 

 and the production of this constituent 

 ceases, and the plants perish. 



The analyses of the ash of plants 

 shows iron, but the quantity is small 

 compared with other ingredients, such 

 as potash, etc., and thus though very 

 impoi*tant, still the quantity requii-ed 

 is not much and usually found in soils. 

 However if the soil where the trees re- 

 ferred to was deficient in iron, no doubt 

 a ready response would be given in a 

 more vigorous and productive tree ; 



