Mat 23, 1919] 



SCIENCE 



499 



The tremendous destruction of game in Cali- 

 fornia is well known, but few probably realized 

 its extent until the actual figures were placed 

 before them. When we read that 72,000 ducks 

 were handled by one Game Transfer Company 

 at San Francisco in the season of 1910-11 and 

 20,000 geese by another company in the pre- 

 ceding year, while the estimated nimiber of 

 these birds sent to market has decreased from 

 350,000 in 1911-12 to 125,000 in 1915-16, we 

 can readily understand why there is serious 

 apprehension as to the future of the game 

 supply ! 



Ducking clubs and their influence upon the 

 preservation of wild bird life come in for very 

 careful consideration. It is freely granted that 

 they provide and maintain better feeding 

 grounds for the ducks while additional food is 

 supplied in the form of '" bait." Indiscriminate 

 and illegal gunnery is prevented on the areas 

 under the club's control and hunting is limited 

 to a few days a week and to relatively few 

 shooters. At other times the grounds form an 

 admirable refuge for the birds. 



On the other hand, the attractiveness of the 

 protected grounds concentrates the duck popu- 

 lation in a limited area where a very heavy 

 toll is levied, and the shooting is done by 

 highly trained marksmen with the best of 

 weapons, and large annual bags result. And 

 the authors consider that the extermination of 

 the ducks is far more rapid than when they re- 

 main scattered over wide areas, and are hunted 

 by gunners of varying skill. 



Other topics connected with conservation are 

 discussed in the same careful manner, while 

 the treatment of the life histories of the vari- 

 ous species is very full. Turning to the chap- 

 ter on the Valley Quail we find, besides the 

 description of the bird, nest, habits, etc., evi- 

 dence to show that the males act as sentinels ; 

 while it is pointed out that the species lays 

 more eggs than any other game bird and suf- 

 fers corresponding mortality and means of 

 controlling the latter are suggested. The re- 

 lation of the species to agriculture is con- 

 sidered carefully and also the problem of hunt- 

 ing this bird for the market. 



This is a work of reference which should be 

 in every western library and one that should 



be available to conservationists the country 

 over. 



The publishers have done their part of the 

 work admirably and the result is a very hand- 

 some volume, beautifully illustrated by sixteen 

 color plates of game birds from paintings by 

 Louis Agassiz Fuertes and Major Allan 

 Brooks. 



W. S. 



SPECIAL ARTICLES 



THE SUSCEPTIBILITY OF A NON-RUTACEOUS 

 HOST TO CITRUS CANKER 



CiiRUS canker is a disease recently intro- 

 duced into the Gulf states from Japan. At 

 present attempts are being made to eradicate 

 this disease entirely in those states, by burn- 

 ing trees on which infections are found, thus 

 eliminating the sources of new infection. 



The senior writer has shown^ that citrus 

 canker is not closely confined to the species of 

 Cities as hosts but affects plants of a large 

 number of other genera of the Rutacese. It 

 is believed that this work has been corrobor- 

 ated by workers in the United States. 



More recently inoculations of plants outside 

 of the Rutacese have been attempted. The 

 lansones (Lansium domesticum) of the M>»li- 

 aceae, a tree cultivated in the Philippines for 

 its edible fruit, was the first non-rutaceous 

 plant employed. Needle punctures made 

 through a suspension of Pseudomonas citri 

 placed upon the actively growing midribs of 

 leaves and upon the petioles and main stems of 

 this plant have produced swellings which later 

 cracked and erruptions of tissue have resulted. 

 In some cases the swellings have been sur- 

 rounded with the yellow halo typical of canker 

 upon citrous hosts. Control inoculations made 

 with river water under the same conditions 

 have remained negative. 



Pseudomonas citri has been reisolated from 

 such lesions, the numbers of colonies in the 

 isolation plates indicating that there was 

 abundant reproduction of the organism in 

 the lansones tissue. 



1 ' ' Further Data on the Susceptibility of Non- 

 Butaceous Plants to Citrus Canker," Journal of 

 Agricultural Research, Volume 15, No. 12, Decem- 

 ber 23, 1918. 



