66 CHAPTERS ON EVOLUTION. 



may perceive a little space to surround it, as if the particle were being 

 separated from the surrounding protoplasm. Soon, the particle, if 

 digestible at all, will disappear through the solution of its substance ; 

 and you will see it no more, save for the little space that remains 

 awhile to mark the place where the work of digestion was carried on. 

 Thus the process of nutrition is subserved by any part of the interior 

 of the animalcule's frame, just as, through any part of the body, the 

 food, in the absence of a mouth, may be ingested and received. 



Nor is it less important to note how the simple acts of sensation in the 

 Amoeba are performed similarly by means which appear all inadequate 

 for their performance. That which distinguishes the animalcule most 

 conclusively from the great majority of its plant-neighbours, is this power 

 of receiving sensations and of acting upon them. But for this power, 

 the animalcule would be essentially in the position of an inorganic or 

 lifeless mass. A solid particle floating about in the miniature sea 

 which contains the Amoeba and its neighbours, impinges upon the 

 soft protoplasm of its body. Upon such a stimulus, the protoplasm, 

 as we have seen, contracts, and the food-particle is duly surrounded 

 and engulfed by the living mass of the animalcule. It may truly 

 be affirmed that the first nervous acts are strictly utilitarian in their 

 nature. Their use and purport is that of enabling the animalcule 

 to obtain its food. Sensation is thus unquestionably present in this 

 low form of animal life. Indeed, there are few, if any, naturalists who 

 would not assent to the statement that an Amoeba, lowly organised 

 as it is, is more highly sensitive than a tapeworm possessing an 

 organisation of some complexity or a Sacculina, which attaches 

 itself to the bodies of crabs, and whose only sign of life consists in 

 the slow pulsations of its bag-like body. 



But this power of receiving sensations is not the only likeness 

 which the Amoeba, in respect of its innervation, exhibits to higher 

 animal life. Its protoplasm not only receives sensations ; it is also 

 able to act upon information received. The mere contact of the 

 food-particle with the protoplasmic body, is but the prelude to the 

 active contractions of its mass, which are directed towards the seizure 

 of nutriment. And thus we become aware of the fact that not only is 

 this power of " contractility," or of acting upon sensations received, 

 the distinctive property of protoplasm, but that in such a power the 

 actions of higher life are closely imitated. The nervous phenomena 

 which, when occurring in higher existence, are collectively named 

 " reflex action," are essentially of a kind similar to those acts which 

 we see taking place in a body composed of a speck of protoplasm. 

 There is the closest parallelism between our acts of withdrawing our 

 head from a blow, or of closing our eyelids from the same cause, and 

 the action of the animalcule in ingesting its food. Both higher and 

 lower organisms " experience " a sensation, and are capable of acting 



