I50 DESIGN IN NATURE 



spermatozoon or male element ; that presented by the ovule or female element ; and by the anthers, elaters, and 

 other parts connected with reproduction. Plants display in a marked degree the globular, concentric, radiatmg, 

 branched, segmented, and spiral arrangements to which I have so strongly directed attention in the present 

 connection. 



The history of the reproductive elements is virtually that of the cell : indeed, to understand the former it is 

 necessary to consider the latter. 



A few additional observations regarding the cell from the reproductive point of view will be useful. While the 

 cell may, for practical purposes, be taken as the structural unit for plants and animals, it would be a mistake to 

 regard it as in any way simple. Each cell and each group of cells display pecuHarities, and are characterised by 

 features of their own. There is, strictly speaking, no such thing as absolutely simple, identical, homogeneous 

 organic matter. 



This seems proved in two ways : (a) by its behaviour while hving ; and (b) by the appearance presented by it 

 when dead. 



Living matter takes in and gives out inorganic matter : it grows, runs a given course, divides, and repro- 

 duces itself. 



Dead organic matter when subjected to the action of powerful stains, in the majority of cases reveals traces 

 of differentiation and structure. 



Even protoplasm presents a reticulated appearance and consists of four or more elements, namely, oxygen, 

 hydrogen, nitrogen, and carbon, with small quantities of sulphur and other ingredients. 



Living matter as seen in cells, cell plants and cell animals, the reproductive elements, &c., presents under high 

 powers of the microscope a great variety of forms— globular, concentric, radiating, branched, segmented, spiral, 

 reticulated, and otherwise. 



The cell has a career and history of its own. It cannot be regarded as homogeneous, as it is composed of 

 a cell wall, protoplasm or cell contents, a nucleus, and, generally, one or more nucleoh. In addition to these are 

 to be noted, in many instances, plastids, an attraction-sphere mth centrosome, vacuoles, metaplasm, chromatin- 

 network, linin-network, net knot (Karyosome), &c. 



The nucleus is, in many cases, a highly complex structure, and runs through many changes which involve 

 differentiation of a kind. 



The changes referred to are generally classed under the term Mitosis (from a thread), and include indirect division 

 of the nucleus involving (a) the formation of an amphiaster ; (b) conversion of the chromatin into a thread (spirem) ; 

 (c) segmentation of the thread into chromosomes ; (d) splitting of the chromosomes, &c. (Flemming, 1882.) 



The cell plants and animals generally display a nucleus, with or without nucleoU, a contractile vesicle, one or 

 more vacuoles, food spaces, &c. 



The reproductive elements — male and female — on which so much depends, are separate and independent entities. 

 They pass through quite a compUcated series of phases before they reach maturity, and when they do reach that 

 state and unite and amalgamate in the act of impregnation, they inaugurate, as already stated, a progressive series 

 of extraordinary and even starthng changes, characterised by cleavages, reunions, intricate processes of weaving, 

 of tissue forming, of organ forming, of modelhng, &c. 



All this, it need scarcely be added, makes for differentiation, division of labour, and heterogeneity. 



To Schleiden and Schwann, as already indicated, belongs the great merit of first directing attention to the cell 

 as the fundamental factor in plants and animals. These investigators announced the cell theory in 1838, and this 

 date marks a new and important era in anatomy and physiology. The cell, as a matter of fact, is itself composed 

 of molecules, and the molecules of atoms ; and it is, strictly speaking, in the atoms and molecules that we nmst 

 search for those properties, peculiarities, and powers which distinguish one cell from another, one plant from 

 another, and one animal from another. To the same source are to be traced the fundamental differences in the 

 sexual elements which determine lineage and transmission by descent. In the atoms and molecules of the cells 

 and sexual elements are stored up, in a potential form, all the properties, peculiarities, and powers which charac- 

 terise the parent or parents physically and mentally. When it is stated that the atoms and molecules of cells are, 

 primarily, the parents of plants and animals, it is not meant that the cells to which they give origin contain in 

 miniature all the parts of future plants and animals. They merely contain, in a latent form, the initiatory matter, 

 which, under guidance and hereditary laws, develops in favourable conditions of food, heat, light, moisture &c. 

 into plants and animals which in all respects resemble their ancestors. 



No provision is made for variations or the perpetuation of variations, which are calculated to introduce 

 confusion, and to subvert or destroy originally created types. When variations do occur, they are, as a. rule, speedily 

 eliminated. Neither is provision made for the introduction of acquired physical and mental peculiarities. In 



