128 DEPARTMENT OF THE NAVAL SERVICE 



(3) On the Physiological Effect of Urea Taken in the Food. 

 (a) Toxic Effect. 



The symptoms of urea poisoning' or asthenic urenia are headache, dizziness, fatigue 

 and weakness (Hewlett, Gilbert and Wickett, 1918). These symptoms "Are rarely well 

 defined when the concentration of urea in the blood is less than 100 mg. per 100 cc. of 

 blood and they are rarely absent when the concentration exceeds 200 mg." The normal 

 amount of urea in the blood is 0.036 to 0.043 mg. per 100 cc. In order to produce a 

 concentration of over 100 mg. per 100 cc. of blood it is necessary to give a dose of urea 

 amounting to 100 to 125 gms. (Hewlett, Gilbert and Wickett). Furthermore this 

 urea is almost entirely eliminated by way of the urine in twenty-four hours and the 

 symptoms last only, a few hours. 



(b) Effect of Repeated Doses. 



T. Addis and C. K. Watana'be (1916) have given urea in doses of 20 gms. per day 

 for three successive days to young healthy adults. The experiment showed that the 

 administered urea had been almost completely excreted at the end of the third day, there 

 being an average retention on the fourth day of only 4.9i6 gm. urea, which was excreted 

 during the next twenty-four hours if no urea were taken. When 40 gm. of urea' were 

 taken on each of three successive days the results were substantially the same, the 

 amount of urea retained, to be excreted on the first day after the administering of urea 

 had ceased, being 4.46 gms. T. Addis and C. K. Watanabe conclude that "The rate of 

 excretion of the administered urea during successive periods of the twenty-four hours 

 showed that the repetition of large doses of urea did not elicit the condition which has 

 been described as kidney " fatigue." 



(c) The Effect of Taking Small Amounts. 



The facts cited in the previous paragraph indicate that there is no injurious effect 

 either during or after the taking of such large doses of urea as 20 or 40 gm. There 

 would seem, therefore, little doubt that the taking of such quantities of urea as would 

 come in a meal of dogfish, say 4 gm., is without injurious effect on normal persons even 

 if repeated on successive days. O. Folin (1911) has fvn-ther shown that there may be a 

 variation in the daily excretion of urea of from 5.6 to S.l gm. in the same person 

 within a few days, which shows that the amount of urea taken into system in a meal 

 of dogfish would not be greater than that which might be added to the body by 

 additional exercise or a change of diet. 



For expressions of opinions with regard to the effect of taking urea in dogfish 

 flesh, see Appendix B. 



(d) Palatahility of Selachian Flesh. 



With regard to the palatahility of the flesh of the spiny dogfish, Sq2ialus acanthias, 

 the common dogfish of the Canadian Atlantic coast, Mr. Indng Field of the United 

 States Fish Commission says :^° " The Commissioners on Fisheries and Game of 

 Massachusetts have personnally reported its palatahility, the lack of odour or "strength" 

 and the good consistency when cooked or canned. They say it closely resembles halibut. 

 The spiney dogfish has in recent years been exploited in England as a valuable cheap 

 food. A writer in a London paper states that the Plymounth council engaged an expert 

 cook to prepare dcgfish for the table with and without ?auce, and that those who 

 partook pronounced it excellent as to colour, flavour and firmness. 



" The dogfishes are no^ only palatable in the fresh condition, but are as good as 

 many other fishes when preserved by the standard methods. The horned dogfish being 



10 Field, 1908, p. 248. 



