So, the egg of bird breathes due to pores in a shell. Oxygen enters egg and the pairs of water and carbon dioxide hatch outside. If pores are much and channel wide, then the interchange of gases passes quickly. If channel long, i.e. shell thick, the interchange of gases goes slowly: than thicker shell, the slower, as an exchange is laboured by viscidity of air. Therefore in the thick shell of pore must be wide, and in thin - narrow. In spite of features of interchange of gases, the concentration of oxygen in blood of embryos of the most different birds is permanent enough. Such is a requirement of their physiology. Consequently, speed with that air enters egg must be some not less threshold size. The anymore egg, the quicker oxygen must enter him. It is related to conformity to law: an egg (and mass of embryo, and his requirement, is in oxygen) volume grows in a cube and area of egg surface - only in a square. An egg size changes for birds from one gram at a humming-bird to kilogram for the African ostrich is a volume of such egg about one and a half liters. Researches of specialists confirmed from the different laboratories of the world that speed of interchange of gases through a shell (or gas conductivity of shell) really increased at the jumbo zing of egg. However dependence appeared not straight proportional. At the tenfold increase of egg mass permeability of shell for oxygen increases only in 6, 5 times. Length of channels, i.e. thickness of shell, does not diminish (it would reduce durability of shell) thus, and increases too, though slower. But number of pores in six hundred gram egg of ostrich in 18 times more than in a chicken egg weighing sixty grames. The eggs of some types of birds lose water some quicker, than it had to be at normal life terms. What does it mean? And those eggs at such kinds are hatched in beyond measure moist terms. It takes place at halcyons, petrels that nest in burrows, for chickens that ovipositor in vegetable heaps-incubators, and also for birds, arranging nests in hollows. Ventilation in burrows and hollows is poor, therefore as far as hatching of eggs humidity increases from evaporation of water, maintenance of oxygen diminishes, and carbon dioxide - increases. So, nestling hatched despite all problems and insoluble contradictions. From nonexistence he passed to life. New life began. In truth all simple in the wild is difficult on the embodiment. We will be thoughtful about it, when once again we will take out a simple chicken egg from a refrigerator. Egg the secret of life is celled in that.
|