KNO\VLJ;i)r,E. 



September, 1912. 



microbes. Hy tlic use of an itif,'i'nioiis apiJar- 

 atus ftir hatchii)},' tlu- cliickeiis and tlicn raisin;,' 

 them for a certain time, lie was able to produce 

 animals which did not contain any microbes in 

 their Ixidies, and they were able to live and 

 appeared to be as health)- as usual. M. Cohendy 

 very kindly furnished us with the present descrip- 

 tion of his method. 



What is needed in the present case is to have a 

 suitable means for raising; the chickens, starting; with 

 the e^';^. and then to allow them to grow under good 

 conditions for several weeks, all the while being c)uite 

 free from microbes. M. Cohendy was ol)liged to 

 take great care in designing an apparatus svhich 

 would carry out this purpose, seeing that it is quite 

 easy for it to be contaminated with microbes which 

 are always floating in the air or are contained in the 

 different substances needed within the apjiaratus. 

 He o|5erated, in the first place, in a special antiseptic 

 room whicli has the walls and floor well sterili;ied so 

 as to reduce the number of microbes in the air to a 

 very small amount to begin with. Then he made 

 the apparatus which is represented in Figure 357, 

 and it serves in the first place as an incubator for 

 hatching the eggs and then as a chamber w here the 

 chickens are able to live as long as may be desired. 

 The main glass cylinder with an inside sheet metal 

 floor serves for the live chickens, and opening into it 

 on the left hand side is a smaller metal chamber 

 used as the incubator. A felt curtain hangs over 

 the opening between these two chambers. The 

 incubator part is kept covered over with a piece of 

 heat- protecting felt. A round metal door in the 

 incubator end allows of putting in the eggs, and 

 there is a second door in the metal chamber King at 

 the other end of the c\linder for taking out tlie live 

 chickens or for putting in grain, sand, and all that is 

 needed here. 



The incubator is kept as usual at the right heat for 

 hatching the eggs, by the use of a small outside gas 

 burner placed underneath. But after the chickens 

 are hatched, it is required to use a lower temperature 

 in the glass cylinder in which thev are to live, so as 

 to keep it at about the same heat as under ordinary 

 conditions. One precaution to be taken is to keep 

 the heat of the chamber at a somewhat lower 

 point than what prevailr in the room, as M. Cohendv 

 found that unless this were done, the vapour within 

 the cylinder will condense and form dew upon 

 the inside, and this runs down and keeps the floor 

 and the sand alwaj-s wet. This he now- avoids by 

 using a worm tube which will be noticed running 

 along the top and inside the cylinder. It has cold 

 water from the main circulating in it, and this water 

 is sterilized along its course before entering the 

 chamber, as an extra precaution. It is also required 

 to supply drinking water to the chickens, and this is 

 done by using a small plate or trough running along 

 under the worm tube. A slight amount of water is 

 always condensed from the chamber upon the cold 

 tube, and this runs down the trough to one end of 

 the chamber where it collects in a small drinkinsi 



vessel. The grain anti sand are well sterilized before 

 putting them into the apparatus so that they are 

 cjuite free from microbes, as is found by suitable 

 tests in the first |)lace. 



Before putting in the eggs, the apparatus as a 

 whole is taken to a sterilizing apparatus, and is put 

 into it and kept at a heat somewhat above the 

 boiling point of water, so as to destroy all the 

 microbes. The two doors of the cylinder are made 

 w ith rubber joints with an extra jjrotection of cotton 

 which prevents microbes from entering. The air 

 also needs to be kept renewed inside the apparatus 

 while the chickens are living, and this is done by 

 using a tube which runs through the laboratory 

 window to the outer air. An air circulation is kept 

 up in the apparatus, using sterilizers in the path of 

 the tubes, so that the incoming air is quite pure. 

 An ingenious method consists in keeping the air 

 pressure inside the apparatus somewhat higher than 

 what prevails outside, so that when it is required to 

 open one of the doors there is a slight outrush of 

 air from the cylinder so as to drive out any microbes 

 which would tend to enter with the air. It is 

 recognised that eggs when in a healthy state do not 

 contain any microbes in the inside. The outside of 

 the egg is well cleaned and sterilised, then three or 

 four eggs are put into the incubator. This requires 

 the utmost care in order to keep any germ-laden air 

 from entering at the same time, and the author 

 makes use of a rubber cloth-covered box which is 

 quite similar to a photographic plate charging box, 

 with holes for the arms. The inside of the box is 

 carefully sterilized, so that this allows of taking the 

 eggs in the hands and by means of the box they 

 are placed within the incubator. The protecting box 

 will be noticed to the left of the apparatus. During 

 the raising, a set of open bouillon tubes within the 

 cylinder showed whether there were anv microbes 

 inside. 



M. Cohendy thus succeeded in raising chickens 

 for forty-five days which were found by analysis 

 of the contents of the digestive organs, blood and 

 various parts, to be free from microbes. A longer 

 time could not be given, owing to the size of the 

 chamber which was very difficult to make even of the 

 present proportions. A number of check specimens 

 were raised in the same way but the usual microbes 

 were allowed to enter. The author's specimens 

 seemed nevertheless to be as healthy as the others, 

 and when taken out into the air their bodies 

 became peopled with disease and other microbes 

 in about twenty-four hours : but, as might have been 

 expected, they did not suffer at all from this, and the 

 change over did not appear to affect them, as thej- 

 grew up to adult size. These experiments seem to 

 show that the preparation of the animal organism 

 for fighting disease microbes is not the result of 

 individual acquisition, but is hereditarv, and the 

 conclusion is that life without microbes is possible 

 for the higher animals, without any bad effect on the 

 organism. It can no longer be said that microbes 

 are a necessary condition for living animals. 



