372 DESIGN IN NATURE 



and independent in their nature. If, however, plants and animals can unaided reproduce themselves in virtue of 

 inherent vital powers, and discharge the highest functions incidental to life, it follows that they may be credited 

 with the power to discharge the minor functions, among which may be included the process of feeding, growing, 

 secreting, excreting, moving, resting, &c. In other words, if plants and animals can in the absence of foreign matter, 

 irritation, and external stimulation perform the major and higher functions of life they may be trusted to perform 

 the minor and lower functions. 



Reproduction is, in all cases, essentially an atomic, molecular, vital process. It is in the atoms and molecules, 

 or the cells formed by them, that the future being, whether plant or animal, finds its origin and source. 



In the higher animals, where there are male and female elements and separate sexual organs, the elements are 

 usually contained in cells. Thus in mammals the ovum and spermatozoon are both cellular in character. In the 

 several orders of plants, reproduction is, for the most part, effected by spores, germs, and seeds which are atomic, 

 molecular, or cellular in character, according to circumstances. It is, however, often effected artificially by detaching 

 and planting or grafting parts of the originals (stems, branches, leaves, &o.) in suitable localities. Plants may also 

 reproduce themselves by means of roots, runners, bulbs, &c. 



It is in reproduction that heredity makes its most indelible impression. Impregnation and fecundation furnish 

 examples of the subtlest and most permanent combinations of living matter. As we cannot see by the highest 

 powers of the microscope the atoms, and the molecules formed by them, or analyse by the aid of any known process 

 in chemistry those practically invisible and intangible entities, we are forced to accept results, which while they 

 cannot be actually demonstrated, are, nevertheless, clear as inferences, deductions, and matters of reason. If from 

 the coalescence of known molecular male and female elements plants and animals always and invariably identical 

 are produced, it follows that in the male and female elements themselves reside or inhere the potentialities necessary 

 to the production of the plants and animals in question. In other words, if the male and female molecular elements 

 positively refuse to form plants and animals essentially differing from those of which they themselves are component 

 and important parts, then it goes without saying that plants and animals, in every instance, only reproduce 

 themselves. 



A fig tree cannot be obtained from a thorn ; a mammal from a reptile ; or a bird from a fish. 

 From two wholly dissimilar male and female molecular elements such as those obtained from the several orders 

 of plants and animals no living thing can be produced. Indeed the limits within which fructification and repro- 

 duction are possible are exceedingly narrow. A mule and a hinny can be produced by cross breeding as between 

 the horse and the ass, but the mule and hinny are invariably barren. 



The reproductive act has features in common in all classes of plants and animals. It is, however, simplest and 

 most easily studied in the lowest forms. Here the new individual is sometimes produced by division and some- 

 times by budding. What is virtually a protoplasmic mass simply splits into two or throws out a process or bud, 

 which in due time becomes detached from the parent, and discharges on its own account all the functions originally 

 discharged by the parent. 



In these cases only one individual and one sexual substance is required for the reproductive process. In other 

 cases one male and one female element are contained in one and the same individual. This is the rule in herma- 

 phrodite plants and animals. In the higher and highest plants and animals, the male and female elements are 

 found in separate individuals. In bisexual plants and animals the male and female elements must be brought into 

 contact either directly or indirectly, and must commingle and interpenetrate before fertilisation and reproduction 

 can take place. Reproduction is undoubtedly an evidence of design and of life. Only living things can reproduce 

 themselves. A crystal forms or may be formed under certain conditions, but it cannot reproduce itself after the 

 manner of a plant or animal. 



It may be convenient at this stage to refer briefly to the several kinds of reproduction. The protamoeba of 

 Professor Haeckel, one of the simplest of living forms, consists, according to him, of a minute albuminous mass. He 

 does not explain whence came the mass or why it divides. On attaining maturity it splits into two, and in due 

 time each half becomes as perfect as the original whole. This is the simplest possible form of reproduction. It is 

 bisection or multiplication by division. This fundamental form of reproduction in certain cases repeats itself ; the 

 two original halves being divided into four, the four into eight, and so on ; the parent, as it were, resolving itself into 

 a swarm. This primary form of division is also seen in the cleavage of the impregnated human ovum. MultipU- 

 cation by division is a vital act, and provision is made for it in the original individual. It is in no sense the result 

 of irritation or of external stimulation. 



Reproduction by budding is sUghtly more complex. This is seen to advantage in cell multiplication in plants 

 and ammals. In the buddmg process the parent sets apart and prepares a certain portion of its substance for a 

 separate existence. In due course the separation takes place, and in such a manner that the parent is in no wise 



