216 THE CANADIAN NATURALIST. [June, 



tain even that only in its insoluble variety. It is, accordingly, 

 on these sands that the richest increase ever obtained by means 

 of sewage has been achieved. It is impossible to infer from this 

 increase what the effect of the Edinburgh sewage would be on 

 the grass-crop of the Rugby meadows ; or on any other crop else- 

 where. Still less can the crops obtained, either at Craigentinny 

 or Rugby, afford of themselves the slightest indication of the area 

 to which the sewage of the British population is due. 



It is not necessary, and it might seem invidious, to pursue 

 these reasonings further, or to trace in minuter detail the erro- 

 neous conditions, which involve in doubt, and render inconclusive, 

 the trials in progress at Rugby. Those trials are carried on by 

 a body of able men, who will doubtless improve their method as 

 they proceed. The reporter however is anxious, in quitting this 

 subject, to record his conviction that no experiments on sewage 

 can determine its value, or settle the problem of its utilization, 

 unless the measurement of its influence on the crop be conjoined 

 with that of its effect on the soil ; unless, in other words, the 

 maintenance of capital receive a share of attention, as well as the 

 increase of expenditure ; unless, to sum up all, we approach this 

 question, not merely in the hope of advantage to ourselves, but 

 also under a deep sense of our duty to posterity. 



Tribute to Messrs. Lawes and Gilbert. — Having spoken 

 in condemnatory terms of the "nitrogen theory," and of the doc- 

 trine of " manurial specifics," and having declared these theories, 

 to the best of his judgment, defunct, the reporter is anxious in 

 justice to add, that their career, if brief, has been brilliant ; that 

 they have been advocated courageously and conscientiously, in 

 single desire to arrive at the truth ; and that the princely experi- 

 ments undertaken for their support, if they have failed in estab- 

 lishing untenable propositions, have nevertheless elicited incidental 

 ^nd collateral results, of very high interest and importance. Twen- 

 ty years of indefatigable labor in a difficult field of research entitle 

 Messrs. Lawes and Gilbert to an ample tribute of public recogni- 

 tion. It is indeed impossible to believe that reasoners so acute, and 

 experimentalists so persevering, will long continue to maintain 

 the slightest remnants of a doctrine so manifestly opposed to the 

 laws of nature. In this respect their eminent antagonist, who, in 

 1845, found himself in a similar predicament, — i. e., in unwitting 



