168 



It "will be seen that the amount required per lb. is only "23 ounces 

 or less than one quarter of an ounce, and if we watch closely the 

 occurrences in the field, it is fairly certain that a Large proportion 

 if not all of this amount may be naturally supplied, by various, 

 apparently small natural agencies, coincident with bird, insect, 

 animal, and plant life. 



To take for granted that it is necessary to supply artificially, a 

 certain amount annually to be taken up by the crops, is therefore 

 untenable: and the necessary amount to be supplied can only be 

 correctly ascertained, by careful experiment. 



It is found that the addition of certain proportions of Basic slag 

 will improve the bearing of a plantation, it will then be the duty of 

 the planter to ascertain, whether the extra cost, is equal to the 

 increase in production. In many instances this will probably be the 

 case, and in some instances the cost of artificial manures will be 

 justified by an increase in production. 



What the planter wants to know is; what is the amount of the 

 natural supply, and what is the right proportion to be added to obtain 

 profitable results. Having ascertained this, his judgment will tell 

 him what course to follow in the application of artificial supplies of 

 plant food. 



A knowledge of the amount of the stored supply may be 

 obtained by chemical analysis ; but the incidental supply evidently 

 cannot be obtained by this means. Once the stored supply is known, 

 the amount required by the plant in addition can be ascertained by 

 experiment, Avhatever may be the amount of the incidental supply. 



From an agricultural point of view the earth is known to contain 

 certain supplies of plant food, some of which exist in an unavailable 

 condition, and may continue so, unless natural or artificial forces an' 

 applied to liberate it ami make it available. 



Analvsis tell its, how much of certain constituents the soil 

 contains, but it is impossible by this means to show how much is 

 actually ready or available at one time or how much becomes available. 

 eacli year, for use of plants: so that although we may know exactly 

 what food is in store, we do not accurately know how much of it 

 becomes available. 



It is clear therefore, that this must be ascertained by experiments, 

 such are already instituted under the direction of the Botanical 

 Department with most encouraging results. 



683 "A STALK-EYED CRUSTACEAN. 



■■ Specimens ot a stalk-eyed Crustacean received at this Offic- 

 from Mr. J. II. Hart, F.L.S , Superintendent of the Royal Botanic 

 Gardens, Trinidad, referred to in the Agricultural News, (Vol. Ill, 

 p. .".SO), have been identified at the British Mu-eum (Natural History) 

 as Hipp a emeriti*, Linn. Mr. Calmon, replying to the. letter of the 

 Imperial Commissioner ot' Agriculture, states that the species 'is 

 widely distributed on the coast of North and South America.' 



