200 COMPOSITION AND ARRANGEMENT 



it is a remarkable example of the economy of force ; a grain of yeast or a grain of diastase is 

 sufficient to change any quantity of sugar into gum or carbonic acid. If there was a mutual 

 combination of elements in this case the force resident in the yeast or diastase would soon be 

 exhausted, and no farther change could occur; it merely disturbs the forces in other bodies, 

 without being affected itself. 



COMPOSITION AND ARRANGEMENT OF VEGETABLE TISSUES. 



The frame work or skeleton of vegetables consists of a net work of interlacing fibrous matter. 

 The organized element in all tissues is a cell. We may enumerate the parts of an organ thus : 

 cell, fibre, tissue, organ. Fibre, is formed of cells, and tissue of fibres, and organs of tissues. 

 A combination of organs make the individual. The simplest indi'V'idual is a single cell. The 

 station which such an individual occupies is the lowest possible. A vegetable then may be 

 regarded as a congeries of cells ; or in truth a congeries of individuals, each of which performs 

 its own function, independent of, but in unison with those of the group. A cell, however, 

 elementary as it appears, does not come into existence by a single act : it is built up in stages, 

 or has its growth and development ; the microscope reveals this. A cell, therefore, is not pro- 

 duced like a crystal, whose particles coalesce, or arrange themselves in one act. A crystal, 

 however, like an organ, is made up of an infinitude of regular and similar atoms ; yet, unlike the 

 force in crystallization, it is internal. If we go back to the earliest stage of development and 

 formuilou, there is a close resemblance in the aetlen cf forces :nc'i;lcr.t to the fcrmaticn cf a 

 crystal and the incipient steps in the cell process : a drop of liquid containing cell matter, and 

 a drop containing crystalline matter, exists under circumstances quite analogous ; condensation 

 in both cases would result in the union of contiguous particles ; in the one case, there would 

 be granules, which may be regarded as the first stage of a cell, constituting a nucleus, in the 

 latter a union of molecules constituting a crystal. When, however, we conceive so much ac- 

 complished, the operation of the forces ceases to be analogous ; the crystal continues to be 

 built up by the union of similar molecules, applied to each other upon external surfaces. There 

 is nothing developed in the interior, as in the construction of a cell. It may be, and probably 

 is wrong to regard even the incipient steps in the formation of a cell as a crystallization. What 

 I mean to say is, that it is only in the incipient stage that the processes resemble each other at 

 all. A crystallization in a tissue is a diseased or abnormal condition ; the formation of crystals 

 called raphides in the vegetable, as in the bark and trunks of trees, interrupts the performance 

 of the functions. Analogous deposites of bony matter in the tissues of the heart and large ves- 

 sels in elderly people is a disease, or an abnormal condition, which produces, in some cases, 

 death. In beings where the principle of life is concerned, it is philosophical to suppose that 

 they are governed by laws quite dissimilar to those which govern matter, in their origin as 

 as well as in their mature forms, however much their phenomena may be alike in certain stages. 

 No doubt changes take place which are invisible, which are truly functional, and not physical. 

 We may, therefore, suppose that in the formation of granules, which precede the cell, the 



