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376 DESIGN IN NATURE<br />
quently little or no hsemorrliage. The union of offspring and parent, although, in one sense, of the most intimate<br />
possible description, is, in another sense, a loose union ; that is, a union of simple apposition, temporary in character,<br />
and dissoluble during any period of gestation. Unless, however, the fcetus be permitted to ripen during mne<br />
calendar months, and the natural period of dehiscence as between the maternal and foetal portions of the placenta<br />
be allowed to supervene, there is apt to be flooding from the rupture of uterine blood-vessels.<br />
During the period of gestation, particularly in the later months, the mammae increase in size, and produce a<br />
rich nutritive fluid (milk), which forms the first and all-sufficient food of the infant.<br />
All the stages through which the impregnated human ovum passes are vital. The impregnated ovum at the<br />
outset consists of two separate, hving elements. They coalesce and unite to form one living being, having in it the<br />
peculiarities and potentiahties, physical and mental, of both parents. The impregnated ovum, the foetus, and the<br />
future infant owe their existence to a series of vital changes which are spontaneous and fundamental in character.<br />
Similar remarks are to be made of the enlargement of the mammae and the production of milk in anticipation of<br />
the birth of the progeny. These changes are in no way caused by irritability of the substances in which they<br />
occur, neither are they due to any form of extraneous stimulation.<br />
In considering the subject of reproduction in the mammal the male and female elements are to be considered<br />
together. They each take part in the process and are equally important. The male element (sperm-cell or sperma-<br />
tozoon) is the product of the testes, and the female element (germ-cell or ovum) that of the ovaries.<br />
Both the male and female elements are cellular in character ; the ovum being a nucleated cell. The ovum<br />
when discharged from the Graafian folhcle of the ovary is very tiny, and just visible to the naked eye. It appears<br />
as a clear speck, and measures xis*^ °^ ^^ ^"^^ diameter.<br />
The changes witnessed in the maturation and fertihsation of the ovum are of the most interesting and instruc-<br />
tive character, and point to an independent and self-directive power in the male and female elements, as well<br />
as a conjoint and interdependent power. They also indicate that the male and female elements act directly on the<br />
protoplasm of the ovum by causing its molecules to aggregate or separate, to converge or diverge, to coalesce or<br />
divide, to involute or evolute, to protrude or recede, &c. The molecules, when fertihsation is a completed act, are<br />
apparently under the joint control of the male and female elements. The male and female elements are evidently<br />
foci of force ; their function consisting in marshalling and arranging the molecules as development proceeds and<br />
new combinations take place. They exercise a formative power, which reveals itself in straight line, curve, circular,<br />
spiral, and other formations seen in the growth of plants and animals generally, and in the crystalline and dendritic<br />
arrangements met with in the physical universe (Plates Ixi., Ixii., Ixiii., and Ixiv. ; see also Plates i., ii., iii., and iv.).<br />
At times the male and female elements, especially the former, exercise what is virtually a magnetic power, whereby<br />
the molecules are attracted or repelled and arranged in straight fines, curves, ovals, elUpses, spirals, circles, &c.<br />
This circumstance points to a much more intimate union as between organic and inorganic matter, and as between<br />
vital and physical force, than is generally suspected. The vital and physical forces work together, and are practically<br />
under the same laws. The fife leads, but it freely avails itself of the matter and forces of the universe.<br />
The changes above referred to take place in the male and female elements of all animals, man included. They<br />
are best seen in the transparent ova of echinoderms and in Ascaris megalocephala, a parasitic thread-worm found in<br />
the horse, in which the various changes can be followed in one and the same ovum.<br />
Professor E. v. Beneden gives a most interesting account of the process of fertilisation, and of the division of<br />
the nucleus in Ascaris (Plate Ixxxviii., page 385). He regards the male and female elements and their chromatin<br />
as distinct, even when in union. Prior to their conjunction the male and female pronuclei each contain two short<br />
chromatin rods {chromosomes) surrounded by a clear nuclear matrix. The rods in question initiate what is virtually<br />
a process of weaving and differentiation. Thus they undergo a series of changes which result in skein and looped-<br />
v-shaped formations ; these being succeeded by new structures which exhibit stellar, radiating arrangements, and<br />
ovoid and circular arrangements.<br />
Concurrently with the skein and looped-v-shaped formations two attraction- spheres make their appearance<br />
between the pronuclei. The attraction -spheres have central spots or poles, around which their molecules are arranged<br />
in a radiating and concentric manner. The poles of the spheres are connected by a chromatin fibre arranged in<br />
the form of a spindle. The attraction-spheres, there is reason to believe, are centres of growth, and plav an<br />
important part in the formation of the daughter cells which are the first product of the divided ovum.<br />
A very considerable degree of differentiation, it will be seen, occurs in the male and female reproductive<br />
elements (pronuclei) and in the attraction-spheres before the fertiUsed ovum is ready for segmentation and the pro-<br />
duction of a new being. The several changes referred to negative the idea that either the male or female elements<br />
are fundamentally simple, homogeneous structures. On the contrary, they differ from each other before they come<br />
into contact. They also undergo several important changes during the fertilising process and before the quickened