454 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



I can accept this as a correct result, because it does not expect more 

 from the microscope tlian that instrument can accomplish, and leave it 

 to my readers to compare it with the result obtained by Dr. Harz. It 

 is evident that insignificant quantities of indeterminable substances 

 cannot be avoided, and every farmer knows that even if he cleans his 

 grain ever so carefully some particles will slip in which do not belong 

 to it. 



Dr. Harz's article, however, causes me to make the following state- 

 ment: To avoid mistakes I must state that the "food-flour" which Dr. 

 Harz examined is no fish-food — would, in fact, be very expensive if 

 used as such — but a dog food manufactured by Goos tor many years. 

 I therefore need not consider it at all in this connection. 



I was greatly surprised by Dr. Harz's statement that the food, after 

 having stood in a room for twenty-four hours, developed a peculiar, dis- 

 agreeable odor. From my own experience I must term this as pure 

 imagination, for I kept this food for at least six months in my study, 

 partly in small pieces and partly in open cigar-boxes, and I could never 

 discover even the slightest odor. Since I moved into my present quar- 

 ters — in October, 1883 — I keep this food in my garret, and although it 

 has become damp during winter, I cannot discover any odor whatever. 

 I also keep a small quantity in my room, for feeding the fish in my 

 aquarium, and cannot notice any odor. It is possible that the food 

 examined by Dr. Harz had for some time been kept in a damp cellar 

 and become infested with roaches and other vermin, which would to 

 some degree explain the result of his examination and the odor. 



Owing to the nature of the ingredients which Dr. Harz thinks he has 

 discovered in the food, he has come to find it expensive, for which, 

 however, I cannot blame him very much, since in my article "on the 

 artificial feeding of carp"* I made use of the expression, "I have not 

 taken into account the cost of producing the food, thus iilacing it at a 

 much lower price." T have corrected this mistake in my article on the 

 same subject in the Baycrisclie Fischerei-Zcittmg, 1883, No. 1, 19-23, and 

 I would recommend Dr. Harz to study this article. He has, moreover, 

 not taken the salt into account. On the other hand Dr. Harz's erro- 

 neous calculation may be excused by the circumstance that he has 

 based it on the cheap ingredients of the food, as erroneously found by 

 him, while it consists of comparatively expensive materials. If Dr. 

 Harz will take into account the cost of production and the salt, and 

 consider that the manuf'acturer wants not only to make the interest on 

 the capital invested in buildings, machinery, implements, &c., but also 

 some net profit, he will hardly find Mr. Goos's price too high. 



A person who manufactures the food himself will of course obtain it 

 cheaper than if he buys it; but whether the gain will pay for the labor 

 is a question which will be answered differently according to circum- 



* F. C. Report 1882, p. 1009. 



