376 DESIGN IN NATURE 



quently little or no hsemorrliage. The union of offspring and parent, although, in one sense, of the most intimate 

 possible description, is, in another sense, a loose union ; that is, a union of simple apposition, temporary in char- 

 acter, and dissoluble during any period of gestation. Unless, however, the fcetus be permitted to ripen during mne 

 calendar months, and the natural period of dehiscence as between the maternal and foetal portions of the placenta 

 be allowed to supervene, there is apt to be flooding from the rupture of uterine blood-vessels. 



During the period of gestation, particularly in the later months, the mammae increase in size, and produce a 

 rich nutritive fluid (milk), which forms the first and all-sufficient food of the infant. 



All the stages through which the impregnated human ovum passes are vital. The impregnated ovum at the 

 outset consists of two separate, hving elements. They coalesce and unite to form one living being, having in it the 

 peculiarities and potentiahties, physical and mental, of both parents. The impregnated ovum, the foetus, and the 

 future infant owe their existence to a series of vital changes which are spontaneous and fundamental in character. 

 Similar remarks are to be made of the enlargement of the mammae and the production of milk in anticipation of 

 the birth of the progeny. These changes are in no way caused by irritability of the substances in which they 

 occur, neither are they due to any form of extraneous stimulation. 



In considering the subject of reproduction in the mammal the male and female elements are to be considered 

 together. They each take part in the process and are equally important. The male element (sperm-cell or sperma- 

 tozoon) is the product of the testes, and the female element (germ-cell or ovum) that of the ovaries. 



Both the male and female elements are cellular in character ; the ovum being a nucleated cell. The ovum 

 when discharged from the Graafian folhcle of the ovary is very tiny, and just visible to the naked eye. It appears 

 as a clear speck, and measures xis*^ °^ ^^ ^"^^ ™ diameter. 



The changes witnessed in the maturation and fertihsation of the ovum are of the most interesting and instruc- 

 tive character, and point to an independent and self-directive power in the male and female elements, as well 

 as a conjoint and interdependent power. They also indicate that the male and female elements act directly on the 

 protoplasm of the ovum by causing its molecules to aggregate or separate, to converge or diverge, to coalesce or 

 divide, to involute or evolute, to protrude or recede, &c. The molecules, when fertihsation is a completed act, are 

 apparently under the joint control of the male and female elements. The male and female elements are evidently 

 foci of force ; their function consisting in marshalling and arranging the molecules as development proceeds and 

 new combinations take place. They exercise a formative power, which reveals itself in straight line, curve, circular, 

 spiral, and other formations seen in the growth of plants and animals generally, and in the crystalline and dendritic 

 arrangements met with in the physical universe (Plates Ixi., Ixii., Ixiii., and Ixiv. ; see also Plates i., ii., iii., and iv.). 

 At times the male and female elements, especially the former, exercise what is virtually a magnetic power, whereby 

 the molecules are attracted or repelled and arranged in straight fines, curves, ovals, elUpses, spirals, circles, &c. 

 This circumstance points to a much more intimate union as between organic and inorganic matter, and as between 

 vital and physical force, than is generally suspected. The vital and physical forces work together, and are practically 

 under the same laws. The fife leads, but it freely avails itself of the matter and forces of the universe. 



The changes above referred to take place in the male and female elements of all animals, man included. They 

 are best seen in the transparent ova of echinoderms and in Ascaris megalocephala, a parasitic thread-worm found in 

 the horse, in which the various changes can be followed in one and the same ovum. 



Professor E. v. Beneden gives a most interesting account of the process of fertilisation, and of the division of 

 the nucleus in Ascaris (Plate Ixxxviii., page 385). He regards the male and female elements and their chromatin 

 as distinct, even when in union. Prior to their conjunction the male and female pronuclei each contain two short 

 chromatin rods {chromosomes) surrounded by a clear nuclear matrix. The rods in question initiate what is virtually 

 a process of weaving and differentiation. Thus they undergo a series of changes which result in skein and looped- 

 v-shaped formations ; these being succeeded by new structures which exhibit stellar, radiating arrangements, and 

 ovoid and circular arrangements. 



Concurrently with the skein and looped-v-shaped formations two attraction- spheres make their appearance 

 between the pronuclei. The attraction -spheres have central spots or poles, around which their molecules are arranged 

 in a radiating and concentric manner. The poles of the spheres are connected by a chromatin fibre arranged in 

 the form of a spindle. The attraction-spheres, there is reason to believe, are centres of growth, and plav an 

 important part in the formation of the daughter cells which are the first product of the divided ovum. 



A very considerable degree of differentiation, it will be seen, occurs in the male and female reproductive 

 elements (pronuclei) and in the attraction-spheres before the fertiUsed ovum is ready for segmentation and the pro- 

 duction of a new being. The several changes referred to negative the idea that either the male or female elements 

 are fundamentally simple, homogeneous structures. On the contrary, they differ from each other before they come 

 into contact. They also undergo several important changes during the fertilising process and before the quickened 



