-1859] WRITINGS OF JOSEPH HENRY. 125 



rapid when light is excluded; an inference borne out by 

 actual experiment. 



Animal Organism. 



Besides plants, there is another great class of organized 

 beings, viz: animals; and as we commenced with the con- 

 sideration of the seed in the first case, let us begin in this 

 with the egg. This (as is well known) consists of a sac or 

 shell containing a mass of organized molecules formed of 

 the same elements of which the plant is composed, viz: car- 

 bon, hydrogen, oxygen, and nitrogen, with a minute portion 

 of sulphur and other substances. Indeed this material is 

 derived exclusively from the animal kingdom. Without 

 attempting to describe the various transformations which 

 take place among these organized molecules, a task which 

 far transcends our knowledge or even that of the science of 

 the day, we shall merely consider the general changes which 

 occur of a physical character. 



As in the case of the seed of the plant, we presume that 

 the germ of the future animal pre-exists in the egg, and that 

 by subjecting the mass to a degree of temperature sufficient 

 perhaps to give greater mobility to the molecules, a process 

 similar in its general effect to that of the germination of the 

 seed commences. Oxygen is absorbed through some of the 

 minute holes in the shell, and carbonic acid constantly ex- 

 haled from others. A portion then of the organic molecules 

 begins to run down, and is converted into carbonic acid and, 

 possibly, water. During this process power is evolved within 

 the shell, — we cannot say, in the present state of science 

 under what particular form; but we are irresistibly con- 

 strained to believe that it is expended under the direction 

 again, of the vital principle, in re-arranging the organic 

 molecules, in building up the complex machinery of the 

 future animal, or developing a still higher organization, con- 

 nected with which are the mysterious manifestations of 

 thought and volition. 



In this case, as in that of the potato, the young animal as 

 it escapes from the shell weighs less than the material of the 



