instance of need for self-imposition of a course that will fulfill its functions, The para- 
mount import of legislation may be an awakening to the fact that science must infinitely 
transcend any modest requirements of society. 
It is inevitable that we should describe the present situation as we have. Research 
is geared only to the future, and respects the present and past only for what they mean to 
the future. Let us allow that the historian would see it differently. He would discern 
marked and heroic progress--progress almost of a kind to have lulled us into a position 
of false security. Tick fever was eradicated from cattle in this country by an unrelenting 
chemical attack on the vectors of the microparasite that caused the disease, Incidentally, 
the almost incredible story of tick fever, like that of the recent screwworm campaign, 
should be studied for its true significance, namely, that no iota of knowledge can be spared 
in developing the attack and, conversely, that no attack can succeed in the absence of an 
enormous body of knowledge. Such stories teach the difficult lesson of today--that 
knowledge is power! 
Any contemplation of antiparasitics developed within the Department, including carbon 
tetrachloride in 1921 and tetrachloroethylene in 1925, both of which promptly became 
invaluable in the treatment of countless thousands of human victims of hookworm disease, 
for which the latter is even today thetreatment of choice, reveals that most of the chemi- 
cal measures against parasites of livestock that have been widely employed in this 
country and throughout the world were developed by the Department. Although the record 
makes one hesitant to name the outstanding veterinary anthelmintic, there can be little 
doubt in informed minds that phenothiazine must be accorded that rank, This drug com- 
bines a unique range of application, a high degree of efficiency, an unusual margin of 
safety, an ease and versatility of administration, and a variation of antiparasitic actions 
not found in any other anthelmintic, 
Only yesterday, notable antiparasitic developments were on the verge of revolution- 
izing standards and concepts of production, performance, feed-conversion, quality, and 
condition of livestock and poultry. These developments, and others, indelibly established 
at the farm level that parasite control is an essential factor in quality and profitable 
production, They also prove, so far as one may judge from the acid test of experience, 
that notable achievement is within reach through adjuvant reliance on foreign chemicals, 
because most, if not all, of these materials in common use today are regarded and 
accepted as safe from a consumer standpoint. 
It is patently unfeasible to present what should be said about antiparasitic chemicals, 
On this account, we have prepared, as an appendix, a ‘‘thumbnail'’ tabular statement of 
parasitisms of food animals from standpoints of chemicals now used against them, in the 
order of their apparent usefulness, with special reference to the fate of these chemicals, 
toxicity, and potential supportive or alternative measures, We may, however, look briefly 
into this substantial aspect by using, as an example, the notable anthelmintic to which 
reference has already been made, namely, phenothiazine, 
Notwithstanding the Department’s role in the discovery of the anthelmintic action of 
phenothiazine and its later contributions to knowledge ofits use, what we say is taken from 
innumerable sources, This is inevitable, since morethan 3,000 publications pertain to the 
antiparasitic action of this compound, 
Phenothiazine has disadvantages, which must be borne inmind if we are to progress, 
It is comparatively expensive; therapeutic doses are bulky; some animals, notably horses 
and swine, are rather susceptible to intoxication by it; treated animals eliminate the break- 
down products as a red dye in theurine and feces, which is alarming although harmless; 
the dye stains the wool of sheep (in which the drug has its greatest overall usefulness); 
and discolors milk, It is also deficient in desired efficacy against some parasites against 
which it is hopefully employed, such as trichostrongyles of sheep and many gastro- 
intestinal nematodes of cattle. Moreover, there has been no adequate determination of 
efficient physical forms of the chemical; its pharmacological actions; its remote and 
long-term effects, or net economic advantages of systems of low-level and free-choice 
es) 
