HYDKOOAMPA StAGNATA. lOo 



an eighth of an inch long ; on the 26th, noticing that 

 one of the oldest pieces of Sparganium seemed de- 

 serted, being well riddled with mines through its 

 length, as well as pierced by numerous little holes in 

 the rind, through which the larvae had entered at 

 first, I isolated it in a saucer of water, and watched 

 to see if any larvae would still come out of it, for 

 their transparency rendered it almost impossible to 

 make sure of their presence or absence by holding the 

 plant up to the light. After a few hours three larvae 

 appeared, now grown to a quarter of an inch in 

 length ; and by pursuing a similar course with other 

 pieces of Sparganium as they became brown, I got a 

 sight of ten larvae by the end of the month. On the 

 11th of September I detected a larva now over three- 

 eighths of an inch long, and turned it into a saucer 

 of water without food in order to secure a figure of 

 it. On the 28th I observed another, now half an inch 

 long, and noticed that there was no colour down the 

 back arising from food within ; this I took as a hint 

 that it had ceased feeding and was preparing to hiber- 

 nate, and on examining other pieces of Sparganium I 

 discovered several larvae already laid up, quite colour- 

 less, and quite torpid; unfortunately, these investiga- 

 tions could be effected only at the cost of killing the 

 larvae examined, for I found they soon died after their 

 rest had been broken. 



However, by the beginning of October I had esta- 

 blished a large cylindrical glass jar, in which several 

 fine plants of Sparganium simplex were growing, no 

 longer floating but erect and robust ; upon these 

 were placed some of the less torpid larvae about an 

 inch or two beneath the water, and I had the satis- 

 faction of seeing them mine their way into the plants 

 until they were out of sight ; the rest, still occupying 

 pieces of Sparganium, were introduced among the 

 growing plants to take their chance. 



The winter proved open and favourable for the 

 experiment, and in due course the plants turned 



