CONCERNING PROTOPLASM. 73 



from the substance which we discern in the animalcule or in the 

 bone-cell. Whatever mental powers are exhibited by man, or by 

 animals which possess a brain or nerve-centres of any kind, are the 

 direct products of the nerve-energy stowed up within the cells of the 

 nerve-centres ; and, as we have seen, protoplasm constitutes the 

 -essential materies of these cells. That differences of function, wide 

 and apparent, exist between the protoplasm of the bone-cell and that 

 of the nerve-cell need not be even alluded to as a fact of primary 

 significance when considering the physiology of these varied organs. 

 But sufficient for our present purpose is the still broader fact which 

 demonstrates the community of protoplasm as the one living essential 

 of the human frame, whether concerned in the work of forming bone, 

 secreting bile, producing movement, or evolving thought. Thus it 

 remains a stable fact of human existence that on the special qualities 

 and properties of the protoplasm or living contents of cells, depend 

 all the actions and the total activity and individuality of our lives. It 

 is by means of protoplasm that the cells of the liver secrete bile ; it is 

 through the properties of protoplasm producing new cells that a 

 scratch heals, or other breach of bodily continuity is repaired ; and 

 it is by means of a peculiar functional development of this same 

 substance that we are enabled " to lay the flattering unction to our 

 souls" that we are the possessors of mind, intelligence, and will. 



It might also be shown, as one of the most curious facts of physi- 

 ology, that we harbour in our arteries and veins thousands of proto- 

 plasmic specks which, when viewed under the microscope, behave as 

 do veritable Amoebae. Such are the " white corpuscles " of the blood, 

 which may be seen to undergo mutations of form strictly comparable 

 to the changes of shape that give to the Amoeba its characteristic 

 aspect, and which alterations, from this resemblance, have been named 

 " amoeboid " by the physiologist. Enough has already been said of 

 the structural composition of the human body to show that it derives 

 its living activity from the protoplasm which is everywhere scattered 

 throughout its tissues, and which represents the typical living centre 

 of each cell or tissue in which it occurs. But the case for the univer- 

 sality of protoplasm, as the true and only medium by which life is 

 exhibited, increases in importance when the early outlines and fore- 

 casts of development are even briefly chronicled. The nearer we 

 approach the primitive condition of living organisms, the more 

 apparent does the similarity between the earliest stages of all 

 organisms become. An Amoeba gives origin to new animalcules by 

 simply dividing its body in two, when each half swims away as an 

 independent being, to begin life on its own account. Here, there is 

 an absolute and necessary identity of substance between the pro- 

 ducer and the produced. But even in higher grades of life, where 

 the process of development is by no, means so simply carried out as 



