THE NATURALIST. 



VOL. III., NO. XXIII.— AUGUST, 1838. 



Remarks on the general structure and habits of 

 invertebrate animals.* 



By Edwin Lankester, M.R.C.S., &c. 



In making the following observations on a department of Natural History, it 

 is perhaps hardly necessary that I should define what is meant by that term ', 

 still as it is used in more senses than one, a word or two upon it may not be 

 deemed inappropriate. In its most extended sense, Natural History means the 

 history of Nature ; and therefore whatever objects or phenomena present them- 

 selves to our minds in the world around us, must be included in it. It is thus 

 a name comprehending all human knowledge. But there is a more limited sense 

 in which it is used popularly, and which will not admit of accurate definition* 

 In fact, in this sense it is applied to any thing generally interesting about animals, 

 plants, and minerals, belonging, speaking correctly, to the sciences of Anatomy, 

 Physiology, Zoology, Botany, and others. 



In its most extended meaning, this term is undoubtedly most correctly used, 

 but custom having sanctioned the latter sense, it is that which had better be 

 adopted. 



In looking over the catalogue of all our knowledge of external objects, we shall 

 find it may be reduced to two great divisions, the first being the knowledge we 

 possess of objects in Nature as mere existences, and the second the knowledge 

 we possess of things in action, and requiring time for the performance of these 

 actions. The former comprehends the external properties of bodies, as their 

 colour, size, form, shape, &c. ; the latter comprehends the changes that may 

 take place in bodies with regard to any of these properties. Now all objects in 

 Nature ought to be observed under these two points of view, and I have men- 

 tioned them here, as such a distinction becomes important, for every natural 

 object possessing, first, certain general properties, as form, size, colour, weight, 

 and place ; and secondly, being capable of undergoing certain changes in these 



* Being the substance of a lecture delivered at the Doncaster Lyceum, April 30, 1838, Mr* 

 M0RKY, Surgeon, in the chair. 



vol. in. — no. xxiii. 3 a 



