264 



National Resources Planning Board 



of the great importance of having workers free of 

 parasitic disease. 



The relation of parasitology to food industries is 

 well known. Often fish are from lakes harboring the 

 larval forms of Diphyllobothrium latum — the fish tape- 

 worm. Fish arc intermediate hosts also of various 

 other parasites of man and domestic animals. The 

 development of the fur-farming industry has brought 

 with it the use of fish as feed for foxes, minks, and other 

 animals. This new and widespread use of fish has 

 been accompanied by serious outbreaks of parasitic 

 diseases. Especially is this true where the fish harbor 

 larvae of the trematode, Troglotrema salmincola, which 

 carries to dogs a virus disease. 



The relation of such a parasite as Trichinella spiralis 

 in pork constitutes a major parasitological problem for 

 the meat-packing industry. The presence of human 

 tapeworm cysts Ln pork and beef (measly pork and 

 beef) is also a constant source of loss and annoyance 

 to the packing industry. 



Quite apart from the direct influence on man, the 

 occurrence of parasitic diseases such as cattle tick 

 fever in cattle, stomach worms and liver flukes in sheep, 

 results in great economic loss to the food industries. 



Waste Disposal 



The wastes of many industries are organic in nature, 

 or at least affect life in the soil or in the water to 

 which these wastes may be added. The disposal of 

 industrial wastes must be accomplished through the 

 use of natural agencies. In many instances these agen- 

 cies cannot be used in their nonnal environment, and 

 artificial systems must be developed for the disposal 

 of the particular waste. A system effective in one 

 coimection may not operate in another, since the kind 

 of organism concerned wiU depend upon the nature of 

 the waste; and since the organisms may differ in their 

 demands, the systems must provide varied environ- 

 ments. Thus, the activated-sludge process for the dis- 

 posal of household sewage and industrial waste should 

 be adapted to each particular problem. 



The disposal of industrial wastes must be accom- 

 plished without endangering the health of man or his 

 food supply. The disposal must also be carried on 

 under such conditions that the area in which it is 

 taking place is not made less attractive for man. 



The loss of fertilizing value connected with the older 

 systems of waste disposal was great. The newer sys- 

 tems seek to leave some part of the organic matter in 

 such form that it can be returned to the land to aid in 

 maintaining the farmer's production of organic matter. 

 Much has been accomplished in this direction. It is 

 very probable that adequate research by chemists and 

 biologists will result in still further conservation of 

 these valuable fertilizing materials. Apart from sew- 



age, there are other waste products to be considered, 

 such as smelter gases, etc. 



Plant and Animal Breeding 



One of the most important advances in biological 

 research in recent years is involved in the discovery of 

 the significance of chromosomes, the gene hypothesis, 

 polyploidy, and in general the mechanism of genetics. 

 The amazing results obtained from the development 

 and application of genetics to the com plant offer a 

 striking example. At present, about 65 percent of the 

 corn acreage in the com belt of the United States uses 

 hybrids which are distinctly superior in yield, resistance 

 to weather and disease and in quality to the open- 

 pollinated varieties of corn. This great movement is 

 a direct outgrowth of the fundamental genetic re- 

 searches on the effects of inbreeding and cross-breeding. 



Without genetic knowledge, hybrid com would prob- 

 ably have been long delayed because the first step — 

 selecting parent lines in self-poULnated stocks — appears 

 to be sharply away from rather than toward the goal of 

 better com. Now the com breeder is approaching a 

 position in which he can synthesize hybrid strains espe- 

 cially weU suited for various industrial purposes — e. g., 

 sirups, dextrose, alcohol, plastics, etc. 



Resistance to Fusarium conglutinans, the fimgus 

 which causes cabbage yellows, is another discovery of 

 gene relationship that makes possible continuance of 

 cabbage production in various old producing regions 

 of the United States in which the soil-borne organism 

 has become thoroughly established. In a similar way, 

 the pea-canning industry has made use of the discovery 

 of a dominant gene conferring immunity to common 

 pea wilt (Fusarium orthoceras var. pisi). Ten years 

 ago the industry was tlu-catened with failure from the 

 lack of a supply of raw matei'ials as a result of the wide 

 prevalence of this soil-borne fungus. Several seed com- 

 panies and experiment stations have since supplied a 

 fidl line of varieties in which this gene is incorporated, 

 so that the problem is no longer important. 



Breeding for disease resistance is only a small part 

 of the work of the geneticists. Among the new devel- 

 opments in this field mention should be made of the 

 production of auto and allopolyploidy by the use of 

 heat, colchicine and various well-known chemical sub- 

 stances, including some of the auxins. An illustration 

 may be mentioned; the seed houses now offer for sale 

 newly developed polyploid marigolds. 



Many examples may be cited from the animal king- 

 dom; the cross-breeding program of the poultry industry 

 is a good illustration of the application of genetics. 



In order to combine the good qualities of two breeds 

 of poultry, the following cross is made: Barred Plym- 

 outh Rock juales are crossed with New Hampshire 

 females. The cross results in a barred, quick-feathermg 



