about the nutrition of crops, the answers to which have long since 

 een absorbed into farming practice, the design was so sound and 



the continuity of the record has been so rigorously maintained that 

 2 results now afford an instructive commentary on the whole 



range of the science of crop prodtictipn. We have by no means 

 :ome to the end of the lesson the Rothamsted experiments can 



teach: every new theory, each extension of our knowledge, finds 



an unsuspected criticism or an illustration in the records that are 



still accumulating. " 



The book, intended for farmers and for the senior students and 



teachers in agricultural schools, is divided into the following 



Chapters: Introductory; Fertilisers containing nitrogen; The 



function and comparative value of nitrogenous manures; Phosphatic 



manures; The function and use of phosphatic fertilisers; The po- 



tassic fertilisers; Farmyard manure; Peruvian guano and other mixed 



fertilisers; Materials of indirect fertilising value; Theories of fer- 



hser action; Systems of manuring crops; The valuation and 



purchase of fertilisers; The conduct of experiments with fertilisers. 



Notwithstanding that cases may be quoted where thf use of pure 

 culture of nodule-forming bacteria has been of great service, 

 generally on newly reclaimed soils, the author states in Chapter II, 

 " at the present time we cannot be satisfied that any improved 

 race of bacteria introduced artificially into the soil has managed to 

 persist and get a real footing in face of the enormous natural bacte- 

 rial flora already existing there." 



At Chapter III, we are reminded, that one of the most important 

 effects upon plants of an excess of nitrogen is their increased su- 

 sceptibility to fungoid attacks of all kinds. Thus, in seasons when 

 rust is prevalent the high nitrogen plots at Rothamsted are markedly 

 the more rusty; the grass plots are also marked by their special 

 rusts; and, again, such a characteristic grass fungus as Epichloe 

 typhina is generally common enough on the high nitrogen plots but 

 ibsent .from the others. "But susceptibility to disease brought 

 >out by an excess of nitrogen is perhaps most strikingly seen at 

 Rothamsted on the mangold plots, though the mangold is a plant 

 which, as a rule, suffers but little from fungoid attacks. In Sep- 

 tember, however, the leaves of the mangolds at Rothamsted that 

 receive an excess of nitrogen begin to be attacked by a leaf spot 

 :ungus, Uromyces betae, which develops rapidly until on the worst 

 plots all the larger leaves turn brown and present a btirnt-up ap- 

 pearance, because the spots of destroyed leaf tissue have become 

 so numerous as to run together." 



