394 DESIGN IN NATURE 



§ 79. Career of the Unimpregnated and Impregnated Human Ovum. 



There is the greatest possible difierence between the unimpregnated and impregnated ovum. The former, 

 although a living thing, dies sooner or later after reaching the uterus, and is, in due course, discharged with the 

 catamenia. The impregnated ovum, on the other hand, quickened as it were by contact with the male element, 

 embarks upon a new career ; upon a series of the most complicated and extraordinary changes with which it is 

 possible for even the professional mind to deal. 



Those who endeavour to explain all physiological action by the theory of irritability and artificial stimulation 

 would doubtless argue that the male element (spermatozoon) irritates and excites the female element (ovum). The 

 argument, if employed, would be a mere assumption. The male and female elements are equally alive : they are 

 independent yet interdependent entities, and are absolutely necessary to each other so far as reproduction is con- 

 cerned. The male element is not more necessary to this act than the female element. They are physiologically of 

 equal value. Their coming together and interpenetration is not due to irritation or extraneous stimulation, as 

 generally understood, but to pre-determined vital arrangements. The male element seeks the female one, and when 

 it finds it, it literally buries itself therein : the lashing, vibratile movements of the spermatozoon cannot be referred 

 to the virtually stationary ovum which, at the outset, is nowhere near. The spermatozoon is endowed with inde- 

 pendent movements, and the ovum is moved along by the action of cilia in the Fallopian tube ; it being arranged 

 that the male and female elements shall infallibly meet. The movements of the spermatozoon, the cilia, and the 

 ovum are all independent of each other. They are simply means to ends, and the palpable outcome of design. 

 There is no need for either irritabihty or stimulation in the case. 



In the whole range of science I question if a better example of design, or of adaptation of means to ends, can 

 be found than is supplied by the history of a human ovum before and after impregnation. The impregnated human 

 ovum runs through a whole gamut of changes, some of them as puzzling as they are formidable. It is to be credited 

 with changes in itself, as well as changes in the mother, of the most far-reaching description, and I venture to assert 

 that not one of the numerous changes referred to can be regarded as accidental or the result of irritation or artificial 

 stimulation.' The changes are in every instance spontaneous, independent, and vital, and they are all foreseen and 

 provided for from the beginning. The changes are the result of co-ordinated movements in the hard and soft parts, 

 partly in the foetus and partly in the mother ; and the changes in the mother keep pace with those in the foetus, 

 so that when the period of parturition arrives the child is free to breathe pure air and regale itself with maternal milk 

 prepared for it beforehand. This production of a nutrient, all-sustaining fluid, constitutes the final stage of a 

 superlatively interesting series of developmental acts. The babe and its milk are no chance products. They come 

 together at precisely the right time, and afford overwhelming evidence not only of a Designer, but also of an over- 

 ruhng and ever-watchful Providence. 



§ 80. Development of the Brain and Vessels of the Body— Placental and Foetal Circulation— Successive 

 Changes witnessed in the Growing Parts. 



It may interest the reader and serve a good purpose if, at this stage, I give a very brief account of the history 

 of an impregnated human ovum. 



The impregnated ovum, when it reaches the interior of the uterus, which it usually does about the eighth day 

 after coitus, is, roughly speaking, about the size of a small pin head, and consists of a vitellus and vitelline membrane ; 

 the germmation vesicle and germinative spot (which are prominent parts of the ovum before it leaves the ovary) 

 having disappeared. The ovum when it first reaches the Fallopian tube measures as nearly as may be ^.i^ of an 

 inch, and when it leaves the tube from J5 to .Jj of an inch. 



The hving, impregnated ovum attaches itself to the living mucous surface of the interior of the uterus, usually 

 its posterior portion. The union is at first of the most casual description. By-and-by it becomes more intimate, 

 but at best it is temporary in character ; the ovum, the embryo, and the foetus, as I pointed out in 1872,i occupying 

 the position of parasites as far as the parent is concerned. They are living things which derive their sustenance 

 from the mother, and when the period of parturition arrives, the temporary, but withal intimate, union is severed 

 by a natural process akin to the separation of the leaf from a tree in autumn. Neither the original union with, nor 

 final separation from, the parent occasions much difficulty, both being natural processes. 



That part of the mucous hning of the uterus which the ovum originally touches, and to which it adheres, is 

 termed the decidua serotina, the parts of the hning in its vicinity the decidua vera, and the parts which are said to 

 curve up over the ovum (a modification which I have never seen demonstrated) the decidua reflexa. When the 

 ovum has comfortably settled itself in the mucous lining of the uterus of the mother, it immediately begins to imbibe 



" Tlie Physiology of the Circulation in Plants, in the Lower Animals, and in JVlan." Edinburgh Medical Jirurnal, 1872-73. 



