Incubator

“ An incubator, considerably increasing as it does the number of chicks that can be hatched, is of course of the greatest value on a farm. We had one, capable of holding sixty eggs; and a "finisher," in which thirty more could be placed. Two paraffin lamps, kept constantly burning, heated the large tank of the incubator; and a thermometer, inserted in the water, had to be carefully watched in order that the temperature of the latter might neither exceed nor fall below 103°. ”

“ Consequently a further simplification is introduced inasmuch as no boiler is required.
The essential features of this incubator are shown in fig. 4. The internal parts of the incubator are insulated by a double wall, the interspace being packed by a non-conducting material, which is not shown in the figure. The incubation or egg-drawer (E) is heated by the warm-water tank (T) . Beneath the egg-drawer is a zinc tray (Z) , so constructed that in the central part the floor is raised up into a short cylinder. ”

“ Into each of these slides an iron drawer 35 cm. long × 12 cm. wide × 22 cm. high forming a self-contained incubator. The drawer is fitted with a wooden form to which is fixed a handle and a numbered label. The thermo-regulating apparatus is the well-known Hearson capsule.
Fig. 114.—Cellular incubator.
Two incubators at least are required in the laboratory, for the cultivation of bacteria the one regulated to maintain a temperature of 37°C., and known as the "hot" incubator; the other, 20° C. to 22°C., and known as the "cool" or "cold" incubator. ”

“ An incubator is a sort of comfortable box which keeps the eggs as safe and warm as a mother hen, so that they come out in three weeks just as if a hen were looking after them. Only an incubator, not being alive, wouldn’t get flurried or excited at any one looking on. Joan was told there were eggs in it which were due to turn into chickens on Thursday or Friday. ”

“ Before staged incubation, as developed by Smith, it had not been practicable to operate incubators of a capacity of more than about 300 eggs. By use of the new method, it is possible to operate successfully an incubator containing as many as 52,000 eggs, and the percentage of eggs successfully hatched by artificial incubation has been materially raised. ”

“ He had dissipated his substance in inventing an incubator that worked with wonderful success till the day the chickens were to come out, when it took fire and burned up, taking with it chickens, barn, house, and furniture, leaving the heaven-born inventor standing in the field, thinly clad, and with nothing left in the world but another incubator. ”

“ When subjected to a temperature approximating that of body heat, the eggs of the earlier stages absorb heat and those of the later stages give off heat. It was pointed out in the opinion in the Snow Case that a demonstrated advantage of the Smith method over that of the earlier type of incubator, in which there was no propelled current of air, is that it facilitates the continuous operation of the incubator through staged incubation, and makes it possible in the process of incubation to increase the number of eggs in a single incubator from a few hundred to many thousands. ”

“ Thus an incubator, to be successful, must be capable of automatically adjusting itself to this heightened temperature.
The drawer of an incubator is a confined space and is usually packed as closely as possible with the contained eggs. The eggs are living structures and consequently need air. This necessitates some method of direct ventilation, and this in its turn necessarily increases the evaporation of water vapour from the surface of the egg. ”

“ But, it is sad to state, there must have been some mistake, for this incubator could not live up to the claim in the advertisement, nor, so far as it is known, is there any incubator which approximates that claim. Some marvelous hatches are written of, but the question is not one of marvelous hatches, so far as it means the number of chicks which manage to come through the strenuous act of exclusion, but the real question of incubation is as to the number of strong chicks, capable of living and growing into an animal which will become a money maker for the man who hatched and raised it. ”

“ The air movement maintained will always be sufficiently brisk, however, to prevent an uneveness (sic) of temperature in different parts of the room.' The reference to an incubator in continuous operation, for deliveries once or twice a week, and to temperature regulation of the egg chamber by a propelled current of heated air, moving at a velocity sufficient to maintain an even temperature, shows that Hastings had the conception of staged incubation long before he built the Brooklyn incubator. ”

“ The person to run the incubator is the first condition of its success. A good incubator requires attention twice a day. One person should give this attention, and must give it regularly and carefully. The farmer's wife or some younger member of the family can often give more time and interest to this work than can the farmer. ”

“ For fear of accidents, as soon as the eggs have been laid they are taken from the nests and placed in a patent incubator to be hatched out. The incubator makes fewer mistakes than the parent ostriches do. ”

“ That is to say, for every hundred eggs we set we must not count on hatching more than fifty chicks. Incubators are a constant care. The most important objection to an incubator is that it is against the rules of most fire insurance companies to allow it to be operated in any building that the insurance policy covers. If the automatic heat regulator fails to work and the heat in our incubator runs up too high we may have a fire. At any rate, we shall lose our entire hatch. The latter is also true if the lamp goes out and the eggs become too cool. ”

“ Many people stand in great awe of an incubator, no matter what its make, and have the feeling that to hatch a fair number of chicks in a machine is almost a miracle. The fact is, however, if the purchaser of any incubator will realize that the manufacturer knows more about the proper way to run it than Tom Jones, [108] or Bill Smith, who may be neighbors, and will follow the instructions as given by the manufacturer, with good fertile eggs, it will be almost a miracle if he does not get at least a fair hatch. ”

“ Below the tank is the incubation drawer (E) , which contains the eggs and also a temperature regulator or thermostat (R) . The tank is traversed by a ventilating shaft (V) , and inserted into this is a smaller sliding tube passing up to it from a hole in the bottom of the incubator drawer. The floor of the incubator drawer is perforated, and beneath it is an enclosed air space which opens into the sliding air shaft just described. Fresh air is let into the incubator drawer from a few apertures (I) at its top. ”

“ With the necessary buildings constructed and the stock selected, the next thing required is the incubator, for I do not suppose the modern poultry grower is going to do his incubating with hens, for the simple reason that he cannot afford to. ”

“ The development of the public hatchery would supply these other 20 chicks more economically and more certainly than the farm incubator, but until that institution becomes established the more ambitious farm poultry raisers are justified in trying an incubator.
The best known incubators in the market are the Cyphers, the Model and the Prairie State. Cheaper machines are liable to do poor work. The following points may help the farmer in deciding whether or not to buy an incubator and in picking out a good machine. ”

“ The incubator is very reliable and may be worked within very narrow limits of variation, provided that the gas-supply be regulated by a gas-pressure regulator, that the height of the water in the tube (T) is maintained by daily additions of a few drops of distilled water, and that the incubator itself be protected from draughts. ”

“ In some forms there is an arrangement to ensure a continuous supply of fresh and moist air, but in the majority the incubation chamber obtains its supply of fresh air vicariously. In some forms the chamber of the incubator is heated by a warm water tank of a simple kind, which extends round all its sides. But in other forms a series of tubes or flues passes through the water in this tank and thus simulates in principle the tube boiler. ”

“ Controls.—The necessity for the existence of adequate controls in all experimental work cannot be too urgently insisted upon. Every batch of plates that is poured should include at least one of the presumably [Pg 416] "sterile" medium; plate or tube cultures should be made from the various diluting fluids; every tube of carbohydrate medium that is inoculated should go into the incubator in company with a similar but uninoculated tube, and so on. ”

“ A large glass tube of 25 cc. height, named a Buchner's cylinder, having a constriction near the bottom, is taken; and about two drachms of the pyrogallic solution are placed in the bottom of it. A test-tube containing the culture is now lodged in the upper part above the constriction. The apparatus is now placed in the incubator at the desired temperature, and the contained culture grows under anaërobic conditions. ”

“ It is found best in all cases to set the eggs in the incubator as soon after they are laid as possible. Where the age of the egg is not known it should be carefully candled, that is, held up between the eye and a light in order to determine its condition. In old eggs, the yolk, on candling, becomes more or less diffused with the white and such eggs are to be rejected for incubator purposes as they are not likely to produce chickens. The fertility of the egg must also be assured before placing in the incubator. ”

“ Before the so-called mammoth incubators were made, the largest-sized machines heated with lamps were used on all duck farms, and an incubator cellar would sometimes contain as many as seventy incubators having a capacity of from 200 to 300 eggs each. Now many of the large farms use the mammoth incubators, with a capacity of from 6000 to 18,000 eggs each. ”

“ Petitioner's incubator differs only in unimportant mechanical details from the infringing machine in the Snow case. In it the eggs are set in staged incubation, at different levels, but in no particular order. They are subjected to circulation of heated air, set in motion by fans, which carries heat units from the warmer to the cooler eggs and maintains the air throughout the chamber at substantially uniform temperature. There is a fresh air intake behind the fans and openings in the ceiling for the exit of foul air. ”

“ The first incubators used there were machines set up on trial by a manufacturer who had invented an incubator which was very easy to operate. This man went to the duck growing district, placed machines on various farms, and went from farm to farm daily to attend to them, until the farmers were fully convinced that the machines would do what was claimed for them. In a very short time the artificial method had displaced hatching with hens on the commercial duck farms, and the business was growing amazingly. ”

“ If larger quantities of blood are required, the animal, after puncturing the vein, should be inverted, an assistant holding it up by the legs. Blood to the volume of several cubic centimetres will now drop from the punctured vein, and should be caught in a tapering centrifuge tube, the tube transferred to the incubator at 37° C. for two hours, then placed in the centrifugal machine, counterpoised and centrifugalised thoroughly. ”

“ Human Incubators.
The first incubator designed for rearing children who are too weak to survive under normal conditions, or who are prematurely born, is that of Dr Tarnier. It was constructed in 1880 and was first used at the Paris Maternity Hospital. Its form is that of a rectangular box measuring 65 × 30 × 50 centimetres (fig. 13) . It is divided into an upper and lower chamber; the former contains the infant, while the latter serves as a heating chamber, and in reality is simply a modified water-tank. ”

“ The heat of decomposition in this remarkable natural incubator, is quite sufficient to hatch the eggs. The young are born fully feathered, able to run at once, and able to fly the day they leave the mound. Contrast their stage of development with that of a pigeon born naked, blind, and helpless, and that of a chick born clothed with down and able to run about. ”

“ In the first place be sure to get fresh eggs, which have not been chilled to death in the nest, and sort out all unfertile ones. After the eggs have been in the incubator two, or at most three days, you can tell every egg that is not fertile. ”

“ Now place these tubes in the incubator and, after two to five hours or overnight, we examine for the clearing up of the supernatant fluid. If the serum in a certain dilution agglutinates, the clumps gravitate to the bottom and the upper part becomes clear. If so desired, these dilutions may be carried on to 1 to several hundred in the same way. It is safer to work with dead cultures instead of living ones. To prepare, take a twenty-four-hour agar slant culture of typhoid or paratyphoid and emulsify in salt solution (about 6 cc. to a slant) . ”

“ All the older studies in embryonic development concern man and the higher vertebrates, especially the embryonic bird, since hens’ eggs are the largest and most convenient objects for investigation, and are plentiful enough to facilitate experiment; we can hatch them in the incubator, as well as by the natural function of the hen, and so observe from hour to hour, during the space of three weeks, the whole series of formations, from the simple germ cell to the complete organism. ”