162 THE AMERICAN BOTANIST 



possess bacterial nodules, but the knowledge has not been 

 very widely disseminated. L. A. Boodle in Kczc Bulletin 

 points out that several Indian plants belonging to this family 

 have wart-like structures on the upper surface of their leaves 

 in which such nitrogen-fixing bacteria occur. The bacteria 

 have been named Bacterium ruhiacearum and have been found 

 plentifully in Pavetta Indica and P. angustifolia. The bac- 

 teria cross from one generation to the next by way of the seeds 

 ill which they lie dormant until a new plant begins to grow 

 when they gain access to its interior through the stomata. 

 Ardisia crispa, one of the Myrsinaceae, is another plant re- 

 ported to have nodules of this kind. 



Owni;rs of Complete; Sets. — Set 74 of this magazine 

 is now the property of Lawrence College, Appleton, Wis. 

 The University of Nebraska has also completed its set by se- 

 curing missing back numbers and now should stand 75th in 

 the list of owners. This set is of interest because it was 

 originally the subscription of the late Dr. Bessey. Mr. F. L. 

 Green, Greenwood. Ontario, Canada, lacks No. 124 (Febru- 

 ary, 1920) to complete his set. If any reader can supply 

 this number, we will be glad to forward it to Mr. Green. 

 The small stock of magazines on hand makes it necessary to 

 again advance prices. After January 1st, 1924, a set of the 

 first 25 volumes will cost $20. 



CocKEE-BUR Poisonous. — Each year new instances of 

 the poisonous nature of plants usually regarded as harmless, 

 come to light. Things have come to such a pass that even 

 the pig has to have a chaperone to keep him out of trouble. 

 Investigations by the United States Department of Agricul- 

 ture show that young cockle-bur plants may prove poisonous 

 to hogs, sheep and cattle. They are especially harmful to 

 young pigs. About a pound and a half of cockle-bur to a 



