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THE AMERICAN NATURALIST [Vol. XLIII 



cussion of its precise genetic relationships unwise and the 

 proposed phylogeny of parasitic flat worms based upon it has 

 therefore only a purely suggestive value. 



The Harben lectures for 1908, which were delivered by Pro- 

 fessor George H. F. Nuttall, of Cambridge, England, have been 

 printed {Jour. Roy. Inst. Pub. Health, July-September, 1908). 

 The topics covered are the ticks and the diseases which they 

 transmit to man and domestic animals; the diseases are among 

 the most important of those caused by animal parasites especially 

 and are due to spirochetes, piro plasma and filaria. Nuttall 's 

 account, which is the most complete resume available in this field, 

 is notably lucid and scholarly in presentation. 



Hexry B. Ward. 



