42 The Study of Animal Life PART i 



died, but remnant cells in the body of each had clubbed 

 together in a life-preserving union so effective that a return 

 of prosperity was followed by a reconstitution of mites and 

 by a plague of them. Of course great caution must be 

 exercised with regard to all such stories, as well as in 

 regard to the toads within stones. Of common little 

 animals known as Rotifers, it is often said, and sometimes 

 rightly, that they can survive prolonged desiccation. In a 

 small pool on the top of a granite block, there flourished a 

 family of these Rotifers. Now this little pool was period- 

 ically swept dry by the wind, and in the hollow there 

 remained only a scum of dust. But when the rain returned 

 and filled the pool, there were the Rotifers as lively as 

 ever. What inference was more natural than that the 

 Rotifers survived the desiccation, and lay dormant till 

 moisture returned ? But Professor Zacharias thought he 

 would like to observe the actual revivification, and taking 

 some of the dusty scum home, placed it under his micro- 

 scope on a moist slide, and waited results. There were the 

 corpses of the Rotifers plain enough, but they did not revive 

 even in abundant moisture. What was the explanation ? 

 The eggs of these Rotifers survived, they developed rapidly, 

 they reinstated the family. And of course it is much easier 

 to understand how single cells, as eggs are, could survive 

 being dried up, while their much more complex parents 

 perished. I do not suggest that no Rotifers can survive 

 desiccation, it is certain that some do ; but the story I 

 have told shows the need of caution. There is no doubt, 

 moreover, that certain simple "worms," known as "paste- 

 eels," " vinegar-eels," etc., from their frequent occurrence 

 in such substances, can survive desiccation for many years. 

 Repeated experiments have shown that they can lie dormant 

 for as long as, but not longer than, fourteen years ! and it 

 is interesting to notice that the more prolonged the period 

 of desiccation has been, the longer do these threadworms 

 take to revive after moisture has been supplied. It seems 

 as if the life retreated further and further, till at length it 

 may retreat beyond recall. In regard to plants there are 

 many similar facts, for though accounts of the germination 



