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forms of plant life like yeast, or animal life like protozoa. Let ns take 

 these rudimentary forms of life ; to all appearance tliey are little pieces 

 of jelly ; microscopic investigation cannot discern any difference of 

 tissues, or any special organs, all it can distinguish at the most is some 

 arrangement of cells. What then distinguishes this as a being, as a 

 living thing, and makes it differeutfrom mere jelly? It has sensation. Watch 

 it -when some small foreign body approaches it, it seems excited, when the 

 body touches it, its jelly-like sul)stauce enfolds it, holds it fast; if the 

 body is capable of yielding nutriment, it is held in its folds nntil it 

 dissolves and becomes incorporate in its system ; birt, observe there are 

 no special nerves to feel with, the whole substance is sensitive ; there is 

 no special digestive apparatus, it appears to absorb nutriment at every 

 point of it^ surface ; and similarly some of these beings appi ar sensitive to 

 light, but there is no separate organism like an eye to receive impressions 

 of light, the whole surface is sensitive. Nay, the amoeba seems to have 

 some sort of p(jwer of locomotion, as it can at pleasure extend part of its 

 jelly-like substance (any part, it does not matter which), into a long 

 process as if it were a leg, and so haul itself along. 



It is impossible to trace in the chain of progress every link, but we 

 will pass next to the coclenterata of which the common sea anemone of 

 our shores may serve as a specimen. Here we have a definite mouth and 

 definite organs intended to bring nutriment to the creature. The 

 echinus or sea egg takes us one stage further. 



We now come to that gi'oup of creatures which Cnvier called 

 articulata and modern zoologists annulosa. Here is a rough diagram 

 of such creatures. In so wide a kingdom, including as it does 

 insects, crustaceans, and worms, extending from a lobster to a butterfly, 

 various degrees of complexity will be seen, and yon observe definitely 

 separated the three systems — blood, digestion, nerves — blood at the top ; 

 digestion in the middle ; nerves at the bottom ; and that is the 

 arrangement throughout this kingdom, and gives it its unity. Here 

 then we have a great step. In the protozoa feelings and digestion 

 and nutrition are processes carried on by any or every part of the 

 body indifferently. liow we have the great differentation — digestive 

 system, blood system, nerve system, and we shall find that in 

 this order they are developed. The first thing that lower animals develop, 

 (and some higher animals most consider), is the stomach, the last thing 

 that they develop is the brain. I^ow we wjU not pay much attention to 

 our digestive apparatus, but — I make the remark rather at haphazard — it 

 seems to me, some of the lower creatures have almost as elaborate and 

 complex an apparatus as we have ; but we will follow first of all the 

 blood in its circulation, and see how organs are specialised for its work. 

 First, there is a feeble fluid which courses slowly through what can 

 hardly be called veins, the whole body does the pumping and the whole 

 surface docs the breathing. Having now traced tliis principle in 

 Biology, let ns return to those illustrations in daily life with which we 

 began, and indeed there is no part of our complex social organization in 



