1010 



SCIENCE 



[N. S. Vol. XXIX. No. 756 



The thermostat is constructed in the form of a 

 V out of strips of brass and hard rubber firmly 

 fastened together. The coefficients of expansion 

 and contraction of brass and hard rubber are very 

 different. Any change of temperature either opens 

 or closes the electrical contact on the right-hand 

 side of the V. The most important item in the 

 economy of this new style of incubator is that the 

 heat is applied to the interior, where it is used 

 and needed. Incubators heated by gas utilize only 

 about half the heat applied, and there is, besides, 

 the danger of fire in operation. 



The most satisfactory heater is made of No. 29 

 30 per cent, alloy german-silver resistance wire 

 wound on a frame which fits into one end of the 

 incubator. Two frames, one in each end, with 58 

 feet of wire on each frame and connected as one 

 coil, afford the most uniform method of heating. 

 The wire can be obtained from the American Elec- 

 trical Works, Providence, R. I. The cotton-wound 

 wire is preferable, for it affords considerable in- 

 sulation. When the heating coils are completed a 

 coat of shellac on the wire and frames serves as 

 an added insulation. The resistance of the wire 

 is 229.9 ohms per 100 feet. The only current that 

 can be used with satisfaction is the alternating 

 or incandescent type with large volume and low 

 intensity. The voltage should be 110 for the 

 length of wire indicated, which will produce about 

 .4 ampere of current. 



Keeping Qualities of Butter — Additional Data: 



Otto Rahn, Michigan Agricultural College, 



East Lansing, Mich. 



Former experiments have proved that rancid 

 cold-storage butter does not necessarily have free 

 acids — indeed the majority of samples had no 

 increased acidity. It seemed probable that the 

 substances causing the taste and odor of rancid 

 butter come from a decomposition of protein. The 

 organisms which in pure culture are able to make 

 butter rancid, such as Bacillus fluorescens lique- 

 facien-s, Bacillus prodigiosus, Oidium lactis, etc., 

 break down proteids easily. The analytical de- 

 termination of soluble nitrogenous substances, not 

 precipitated by tannin, copper sulphate nor phos- 

 photungstic acid, gave the highest increase in the 

 butter sample which scored lowest. 



Experiments have been carried on to ascertain 

 if unsalted butter did not keep better in cold 

 storage than salted butter. The supposition was 

 that the water and buttermilk of the unsalted 

 samples would freeze, thus preventing any action 

 of microorganisms, while the concentrated brine 



of salted butter has a very low freezing point. 

 The result was that the unsalted samples did not 

 keep, probably because not all the water was 

 frozen. The unsalted samples scored lower and 

 showed a greater increase of soluble nitrogen. 



The only microorganism which multiplied with- 

 out doubt in cold-storage butter and which occurs 

 in almost every butter sample, is a small Torula. 

 This Torula is the only microorganism of our but- 

 ter samples which can develop on agar with 15-30 

 per cent. salt. A small Torula has been found by 

 Rogers in fishy butter. A Torula is present 

 almost in pure culture in salted herring and may 

 be the cause of its characteristic taste and odor. 

 The description of the Torulce is incomplete, how- 

 ever, they do not disagree. 

 Bacillus lactimorbi, Jordan and Harris [nova 



species) — Its Relation to Milk-sickness and 



Trembles: E. 0. Jordan and N. MacL. Habbis, 



University of Chicago, Chicago 111. 



This organism appears to be a hitherto unde- 

 scribed bacterium and was isolated by the writers 

 from several cases of trembles in cattle, from one 

 case of the disease in a horse, from two lambs 

 and from four cases of milk-sickness in the human 

 subject. It would seem that the disease in man 

 is incurred through the ingestion of infected milk, 

 milk-products or of meat; in animals by the 

 eating of infected pasturage or by drinking in- 

 fected water, the contamination of these being 

 from the soil in which the bacterium has its abode. 



By means of pure cultures the writers have 

 succeeded in reproducing the essential features of 

 the naturally acquired disease in young rabbits, 

 dogs, calves and one horse; cats and lambs have 

 been infected with the production of pathological 

 lesions, but without any well-defined clinical 

 symptoms. 



The organism causing the disease is a strict 

 aerobic, flagellated, sporing, liquefying bacillus 

 about the size of the anthrax bacillus, and 

 very strongly resembling the tetanus bacillus 

 in its most characteristic form. It is, how- 

 ever, very prone to undergo considerable varia- 

 tion in morphology due to methods of culti- 

 vation, temperature and fluctuations in reaction 

 of the media being chiefly responsible. Stained 

 with methylene blue the typical tetanus-like bacil- 

 lus shows well-marked polar metachromatic gran- 

 ules, with at times a central one. It grows either 

 very vigorously or delicately on agar, depending 

 upon whether it is incubated at 25°, 30° or 37° C. 

 Colonies on agar are of a streptococcus type ac- 

 companied by a film growth of a delicate nature, 



