604 



MAN AS A CONQUEROR 



and animal parasites. In addition to the field workers, hundreds of 

 research workers in government and state laboratories are investigat- 

 ing problems connected with conservation. Some of these relate to 

 soil, insects, plant diseases and methods of overcoming them, while 

 others are problems requiring a genetical approach. Bacteriologists 

 and plant pathologists are discovering bacteria or fungi that are 

 inimical or restrictive to species of their kind causing damage. An 

 example of such work has recently come from the laboratory of the 

 University of Idaho School of Forestry, where it has been found that 

 the white pine blister fungus, a serious enemy of the white pine, can be 

 destroyed by another fungus which is parasitic upon it. Investiga- 

 tions are only beginning in this fertile field. 



The Bureau of Fisheries 



This Bureau is concerned with the propagation of various types of 

 commercial and game fishes, as well as shellfish. During recent years 

 research problems have covered three major fields, marine and fresh- 

 water fisheries investigations, agricultural investigations, and investi- 

 gations on shellfish. 



Under the first heading are studies concerned with the conservation 

 and replenishing of cod, haddock, mackerel, and other salt-water fishes, 

 as well as of trout and salmon, together with various problems relat- 

 ing to other fresh-water fishes. In the second group are the problems 

 relating to the improvement of feeding and breeding trout, the treat- 

 ment and cure of diseases of hatchery fishes, studies on fish nutrition 

 and investigation of inland waters with respect to pollution. In the 

 third group of investigations is the propagation of the pearl mussels, as 

 well as surveys of the waters in our various National Parks. Fortu- 

 nately the work of this department appears to be better correlated 

 with the programs of the various State conservation departments 

 than some other governmental agencies. 



During the year 1933 a total of ninety-one agencies were concerned 

 with the output of fish for the Federal government. These agencies are 

 recorded as having distributed the astounding number of 7,202,155,600 

 fish and eggs. 



One of the most interesting problems facing the fish-culturist is 

 the question of how many of the planted eggs and fish can survive. 

 Although over 2,000,000,000 artificially fertilized eggs of the cod are 

 released every year, it is doubtful if this helps nature to any great 

 extent. When it comes to the question of stocking with fish eggs, 



