Scientists and Philosophers 211 



observe that I was a bit of an ass, or make any other such 

 remark, which would have been perfectly justified. He 

 was a realist then, as always. 



Professor Nathaniel Southgate Shaler was a curious, 

 lovable figure. He offered a so-called research course and I 

 happened to be the only student in it the year of his death. 

 It was during my study with him at his home that he told 

 me a memorable story. I wish I could conjure up a picture 

 of our meeting. Shaler was slender, all wire. He spoke 

 rapidly and with great precision of utterance, and from 

 time to time he stroked his beard and then ran his hand up 

 the front of his head, so that his hair frequently stood up in 

 a way which matched his beard quite strikingly. His plan 

 was to prepare a simile to present in one of his lectures in 

 Geology 4; he wished to illustrate the fact that it was 

 fortunate indeed that we had the phenomenon of death. 

 What, he argued, would the earth be like if every animal 

 that had ever been born had continued to live forever? 

 I allowed that it might be difficult to make this most 

 unhappy possibility very vivid. "Nonsense," replied Shaler, 

 "I have thought of an example. Given a single partheno- 

 genetic plant louse, one of those little bugs which can re- 

 produce its kind without the presence of the opposite sex. 

 Now, if all the progeny of a single plant louse should live, I 

 have calculated that at the end of a year we should be 

 faced with a column of plant lice having a diameter 

 equivalent to the distance from Quincy to Brattle Street 

 and thrusting itself upward through space with three times 

 the velocity of Hght." Having made this perfectly astound- 



