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The Message of Science. 89 



laboriously, with an exertion of all their powers, they con- 

 trived to reduce, digest, and in part assimilate. It was a 

 hard life into which they put all their energies ; and to 

 their humble efforts we owe a debt of far-off sympathy. 

 One can but think softly of those first toilers in the archaic 

 marshes so much depended on them. 



The protozoon had his small stomach, an improvised 

 colon, and maybe a unicellular liver; and beyond doubt 

 our ancestral rhizopod had his colics and his jaundices, 

 and was often in mortal agony from terrific peritonitises. 

 It could hardly be otherwise, considering what awful food 

 chunks his hunger drove him to surround. But he strug- 

 gled through, by hook or crook, and finally drifted into 

 metazoic cooperation ; and thus took life a little easier. 



For after locomotion, better food was the first problem 

 which multicellular creatures undertook. The animal 

 organism, with its blood-circulatory, blood-corpuscles, 

 blood plasma, cardiac apparatus for propulsion, and lung 

 tissue for aeration, offers a most interesting and suggestive 

 study of the way the protozoon, in its later r61e of physio- 

 logical cell, has handled the food question. It is the 

 object lesson of the protozoon to the human metazoon. 



To secure better assimilable food for brain and muscle the 

 confraternities of metazoic cells, very early in the division of 

 labor, constrained a certain number or tract of cells to act at 

 first hand on food substances and make that their peculiar 

 business, so as to get it in more available form ; these 



