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THE POPULAR SCIENCE MONTHLY. 



ish dairymen keep their cows tethered dur- 

 ing the summer in " splendid clover and rye 

 grass," and feed them in winter exclusively 

 with clover hay, linseed-cake, and rape-cake. 

 The milk is set in such a way that the cream 

 shall be got off while it is still perfectly 

 sweet, for they will not churn it if it is in 

 any other condition. The proper tempera- 

 ture for churning, which is from 51 to 60, 

 is essential, and the churning should not be 

 continued too long. The best butter-makers 

 stop churning at the very moment the but- 

 ter appears in the form of grains like shot. 

 They pass off the buttermilk through a 

 strainer, then put the butter back with wa- 

 ter, give it a few more turns in the churn, 

 strain again, and repeat the operation till 

 the water runs off as clear and bright as 

 when it is put in. Salt is added by weight, 

 at the rate of six pounds of salt to a hun- 

 dred-weight of butter, by being sprinkled 

 over the butter after it has been spread out 

 in layers ; a few turns are given the mass 

 with the butter-worker, and the process is 

 complete. 



Diffusion of Bacteria. M. Miguel has 

 learned from his investigations of bacteria 

 and germs in the atmosphere that the number 

 of bacteria, which is small in the winter, in- 

 creases through the spring, and becomes 

 large in the summer and fall, then dimin- 

 ishes again during the months of frost. The 

 same is the case with the spores of fungi ; but 

 while the molds are abundant during moist 

 periods, the number of aerial bacteria then 

 becomes very small, and does not increase 

 again till the soil has been dried, precisely 

 when the fungoid spores are rare; so that 

 the maxima of mold-microbes and the mini- 

 ma of bacteria-microbes correspond with 

 each other, and vice versa. While in the 

 summer and fall a thousand germs of bac- 

 teria may often be found in a cubic metre 

 of air, in winter the number falls to four or 

 five, and on some days the dust from two 

 hundred litres of air is incapable of causing 

 the infection of the most alterable liquors. 

 Usually, in M. Miguel's laboratory, the dust 

 of five litres is enough to cause infection, 

 and in the sewers of Paris the particles in 

 one litre will do it. A comparison of the 

 number of deaths in Paris from infectious 

 diseases with the number of bacteria pres- 



ent in the atmosphere showed that every 

 increase of bacteria in the air was followed 

 in about eight days by an increase of the 

 deaths in question. M. Miguel further rep- 

 resents that he has found that the water- 

 vapor which rises from the ground, from 

 rivers, and from masses in full putrefaction, 

 is always micrographically pure, that gases 

 from buried matter in the course of decom- 

 position are always exempt from bacteria, 

 and that even impure air sent through pu- 

 trefied meat is purified under certain condi- 

 tions. 



The Thread-Worm of the Dog. The 

 cruel thread-worm (Filaria intimitis) of the 

 dog was described thirty years ago in the 

 " Proceedings " of the Academy of Natural 

 Sciences of Philadelphia, and has since 

 been repeatedly noticed as infecting dogs 

 in Europe, India, China, Japan, and this 

 country. The heart of a dog, with the 

 ventricles stuffed with the worms, is pre- 

 served in the Museum of the University of 

 Pennsylvania. A specimen of the heart and 

 part of one lung of a dog containing the 

 worms has recently been sent to the Acad- 

 emy of Natural Sciences, by Mrs. Laura M. 

 Towne, of Beaufort, South Carolina, who has 

 also furnished a description of the symp- 

 toms shown by dogs afflicted with the para- 

 site. She had lost several dogs, and a gen- 

 tleman living on a neighboring island had 

 lost more than thirty hunting-dogs in two 

 or three years with the same symptoms. 

 The most characteristic symptom appears 

 to be a peculiar cough, which is excited by 

 any movement, especially after sleeping, 

 ending in a violent effort to bring some- 

 thing from the throat, but nothing is thrown 

 up. When they began to run violently, the 

 afflicted dogs would fall down and become 

 stiff and insensible, but would in a short 

 time get up and renew the chase. A large 

 Newfoundland dog grew ill, exhibiting the 

 drowsiness, lassitude, and inclination to turn 

 round and round when he attempted to go 

 anywhere, which marks the conduct of sick 

 dogs, and finally became subject to spasms. 

 He was examined after death, when one 

 filaria was found lying at full length in the 

 windpipe, and others were found stretched 

 at length and crowded closely in the large ar- 

 tery. Upon cutting into the heart, the worms 



