CHAPTER I 



THE PLACE OF THE HIGHER ANIMALS, 4* OF 



MANKIND IN PARTICULAR, IN THE GENERAL 



SCHEME OF ANIMAL REPRODUCTION 



A MONG the life that swarms in our southern waters, 

 /% there is a charming tiny animal called Cothurnia, the 

 ^ %. buskin animalcule. These creatures cling by thou- 

 sands to the vegetation on wharf piles in our harbors, and 

 can be brought into the laboratory on a bit of seaweed in a 

 drop of water. Because a single Cothurnia is much smaller 

 than the printed period at the end of this sentence, it must 

 be watched through the microscope (Fig. 1). It consists of 

 a graceful transparent cup (formed more like a wineglass 

 than the classical buskin from which it got its name) which 

 is attached by its stem to some larger object. Inside the cup 

 and fixed to its base is a single animal cell, shaped like a 

 trumpet. While the stem sways gently in the water, the cell 

 projects from the cup. Into its open gullet particles of food 

 are swept by a brush of beating lashes or cilia and drift down 

 into the jelly-like cell substance until they are dissolved and 

 digested. 



This simple career of food-gathering is interrupted from 

 time to time by a few hours devoted to reproduction. Our 

 pretty little trumpet withdraws itself inside the cup, rounds 

 up a bit, and slowly separates into two cells by dividing 

 lengthwise. For a time, both cells resume the task of feeding, 

 but afterward one of them retires into the cup and begins a 

 struggle to get away. It pulls so strongly, indeed, upon its 

 stalk that its shape changes; from a trumpet it becomes a 

 shoe. The cilia change position so that they can serve for 

 propulsion in swimming. At last the cell breaks from its 

 attachment and slips out into the sea, ultimately to settle 



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