to appreciate parasites and 

 endocommensals as a valu- 

 able part of biodiversity, but 

 by most estimates they 

 make up between 60 and 

 70 percent of all species on 

 Earth. I can't help but 

 wonder what magnificent 

 flukes, nematodes, and 

 tapeworms once inhabited 

 the great dinosaurs, the 

 massive ground sloths, or 

 the great diversity of early 

 lobe-finned fishes. 

 David Zeigler 



University of North Carolina 

 Pembroke, North Carolina 



Sharp Medicine 



In his article on porcupine 

 quills ["Smart Weapons," 

 3/06], Uldis Roze measured 

 the large force needed to 

 pull a quill out of an animal's 



skin. I, too, have had the 

 discomfort of watching a 

 young veterinarian pull 

 quills out of the long nose of 

 my dog. He did indeed have 

 to pull quite hard! 



But I was told by an el- 

 der vet that the struggle had 

 not been necessary. If the 

 young vet had clipped the 

 quills, enabling the air in 

 them to escape, they would 

 have collapsed and been 

 much easier to pull out. 

 Tana Hemingway 

 Mesqnite, New Mexico 



Uldis Roze replies: In 

 spite of the old vet's sugges- 

 tion, porcupine quills are 

 not hollow — they are filled 

 with a spongy matrix that 

 keeps them from collapsing 

 when clipped. In fact, clip- 



ping the quills increases 

 their danger to the victim. 

 A clipped quill may splinter 

 in such a way that it can't 

 be held by pliers. Then the 

 broken tip may break free 

 and travel in the body. Tana 

 Hemingway should "stick" 

 with the young vet. 



Runaway Inflation? 



In Robert H. Mohlen- 

 brock's article, "Along the 

 Pothole Trails" [6/06], an 

 extra zero has crept into the 

 text. In describing Interstate 

 State Park, he states that 

 Lake Superior is 1 ,000 

 miles away. 



According to my trusty 

 road atlas, and my odome- 

 ter, the distance between St. 

 Croix Falls, Wisconsin, and 

 the western end of Lake 



Superior is only 100 miles. 



Robert D. Esko 



South St. Paul, Minnesota 



Correction 



The locator map that ac- 

 companies Robert H. 

 Mohlenbrock's article, 

 "Along the Pothole Trails" 

 [6/06], incorrectly places 

 the area of detail. The area 

 is north of St. Paul, Min- 

 nesota, not south. 



Natural History welcomes 

 correspondence from readers. 

 Letters should be sent via 

 e-mail to nhmag@natural 

 historymag.com or by fax to 

 646-356-6511. AH letters 

 should include a daytime 

 telephone number, and all 

 letters may be edited for length 

 and clarity. 



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