8 Itev. P. Keith on the Structure of Living Fabrics. 



the spindle and clock into one whole, and so as to dispense with 

 the band and pulleys : he would also see where to introduce 

 the proper contrivances for adjusting the various parts. 



This instrument may certainly be executed at much less 

 expense than that of Dr. S'Gravesande, and I think it will be 

 much more easily and correctly adjusted. It should be al- 

 ways provided with a second mirror, as at lm 9 fig. 2, by which 

 the pencil of light may be thrown in any direction which may 

 be desirable : in many optical experiments, however, the se- 

 cond mirror will be unnecessary. 



IV. Of the Structure of Living Fabrics. By the Rev. 

 Patrick Keith, F.L.S.* 



HPHE structure of every living fabric is composed partly of 

 -*■ solids, and partly of fluids. The solids are the substances 

 which constitute the several parts or organs that give form to 

 the fabric, as the head, feet, limbs and trunk of animals; or 

 the root, trunk, leaves, and flowers of vegetables. The fluids 

 are substances absorbed or imbibed from without, or formed, 

 secreted, or exhaled from within, — as chyle, blood, lymph, 

 urine, — sap, nectar, cambium, expressed juice. While life 

 remains the fluids are in motion, except in the very singular 

 case of the hybernation of some animals, and perhaps of some 

 plants ; or in the equally singular case of some very vivacious 

 animalcula, which, though left on the stage of the micro- 

 scope till they have shrunk, by the evaporation of the fluid in 

 which they were placed, to a mere dry and shrivelled-up mem- 

 branei will again revive and move as at first, upon the appli- 

 cation of a little fresh water. The same thing happens to 

 many of the mosses, which will revive and recover their ver- 

 dure when moistened with water, even after having been com- 

 pletely dried, and kept in a dried state, for many years. 



The perfection of the individual is in the ratio of the com- 

 plexity of its organization. The fewer the organs, the fewer 

 the faculties with which the individual is endowed. This is 

 very evident even on the most superficial survey of the grand 

 divisions of the empire of animated nature. Look at any in- 

 dividual, or at any group of individuals, belonging to the 

 vegetable kingdom. Where are the organs of locomotion ; 

 where are the organs of sense ? They are organs of which 

 the vegetable is altogether destitute. Look at any individual, 

 or at any group of individuals, belonging to the animal king- 

 dom, and the organs of sense and of locomotion are the first 



* Communicated by the Author. 



