18 THE PRESENT CONDITION 



with one another, and from that conjunction, from that 

 union which then takes place, there results the forma- 

 tion of a new being. At stated times the mare, from a 

 particular part of the interior of her body, called the 

 ovary, gets rid of a minute particle of matter comparable 

 iu all essential respects with that which we called a cell 

 a little while since, which cell contains a kind of nucleus 

 in its centre, surrounded by a clear space and by a 

 viscid mass of protein substance (Fig. 2) j and though 

 it is different in appearance from the eggs which we are 

 mostly acquainted with, it is really an egg. After a 

 time this minute particle of matter, which may only be 

 a small fraction of a grain in weight, undergoes a series 

 of changes, — wonderful, complex changes. Finally, upon 

 its surface there is fashioned a little elevation, which 

 afterwards becomes divided and marked by a groove. 

 The lateral boundaries of the groove extend upwards 

 and downwards, and at length give rise to a double 

 tube. In the upper and smaller tube the spinal marrow 

 and brain are fashioned ; in the lower, the alimentary 

 canal and heart; and at length two pairs of buds shoot 

 out at the sides of the body, and they are the rudiments 

 of the limbs. In fact a true drawing of a section of the 

 embryo in this state would in all essential respects 

 resemble that diagram of a horse reduced to its simplest 

 expression, which I first placed before you (Fig. 1). 



Slowly and gradually these changes take place. The 

 whole of the body, at first, can be broken up into "cells," 

 which become in one place metamorphosed into muscle, 

 — in another place into gristle and bone, — in another 

 place into fibrous tissue, — and in another into hair; 



