160 EXPERIMENT STATION EECOED. 



Bocky Mountain spotted fever, L. D. Fricks {Pub. Health Rpts. [U. 8.], 

 29 {191Jf), No. 17, pp. 1008-1020}.— This progress report, dealing with investi- 

 gations made during 1912 by the late T. B. McClintic, relates to infective ticks 

 in nature, the discovery of immune ground squirrels (Citellus columbianus), 

 susceptibility and inununity experiments with woodchucks {Mannota flavi- 

 venter), etc. 



The experiments seem to indicate that a tick attaching itself to a woodchuck 

 at any time within a period of 11 days after its inoculation would become in- 

 fected. In a series of experiments with rock squirrels {Callospermophilus 

 lateralis cinera.^cenfi) , which had been injected with spotted fever virus, foiu- 

 transmitted the infection to guinea pigs through the injection of 0.75 cc. of 

 heart blood on the fifth day. 



It is stated that there is no evidence to support the belief that the mountain 

 goat can acquire or transmit Eocky Mountain spotted fever infection. 



FOODS— HUMAN NUTRITION. 



On certain changes in the composition of the nitrogenous constituents of 

 njeat extracts, A. M. Wright {Trans. New Zeal. Inst., 43 {1910), pp. 7, 8). — 

 Analyses are reported of extract liquor before concentration, of extract pre- 

 pared in an open pan, and of extract prepared in a partial vacuum, and the 

 differences in the chemical composition between the resulting product and the 

 original substance discussed. 



In the case of the extract made by the vacuum method, " the proportion of 

 the organic matter decreases, while the miuei-al salts increase; othei'wise the 

 composition of the vacuum-evaporated extract is very nearly that of the origi- 

 nal liquor calculated to a 20 per cent moisture content, the acidity, insoluble 

 and coagulable proteids, proteoses, and total meat bases being present in about 

 the same amounts in each case. In the original liquor there were no peptone- 

 like bodies, whereas in the vacuum-concentrated extract there were found 0.31 

 per cent of these substances. 



" The extract concentrated in the open pan is very different in composition 

 from either the original liquor or the vacuum extract: The proportion of the 

 organic matter has decreased, and the mineral salts inci-eased considerably; 

 the total nitrogen remains about the same, but the forms in which the nitrogen 

 is present have undergone considemble change; about three-fifths of the in- 

 soluble and coagulable proteids have been rendered soluble and converted to 

 other nitrogenous substances ; there is a decrease in the amounts of proteoses 

 and meat bases; while against these decreases there is found 8.69 per cent of 

 peptone-like bodies which are absent in the original liquor, and present in the 

 vacuum extract to only 0.31 per cent. The acidity has increased by over 3 per 

 cent. 



" The peptone-like bodies and polypeptids are bitter in taste, and it is found 

 that extracts containing relatively large amounts of these bodies have a de- 

 cidedly bitter taste. . . . 



"As but very small amounts of peptone-like bodies are present in vacuum- 

 concentrated extract, and but little change in the composition of nitrogenous 

 bodies is found, it is probable that the prolonged action of heat on the nitroge- 

 nous material in the presence of the normal flesh acids and salts, the amount 

 of which increases as the evaporation proceeds, is the cause of the marked 

 change in composition found in the open pan concentrated extract. The so- 

 called ' burned ' flavor sometimes found in meat extracts is doubtless due to 

 the same cause, for in vacuum-concentrated extract no such undesirable flavor 

 is noted." 



