THE A ME RICA X NA TURA LIS T. [Yo l . XX XV 1 1 . 



takes place, were placed in the stone basin of a fountain. The 

 food supply was scanty or none ; but there was more or less 

 shade and a continual spray of cool water. Here, it was thought 

 growth could be delayed and the larvae kept for later experiment. 

 Yet on the eighth day the astonishing fact was discovered that 

 many were in metamorphosis. And on the fourteenth day three 

 adults, 9.5, 10 and 11 cm. long respectively, were found. 

 Others had probably escaped ; as, despite the perpendicular stone 

 ascent of several inches, it was found they could do. 



I have instanced this series of experiments, first, because of 

 all I have conducted, it is the most favorable to the received 

 hypothesis. Second, because it will serve to illustrate further 

 points as well. It will be noticed that there is a slight apparent 

 acceleration in the metamorphosis of the five larvae placed#with 

 their backs out of the water ; yet some of those in the aquaria 

 with abundance of water began quite as soon and finished but a 

 day or two later ; all that were strictly assorted as to size and 

 other character^ followed suit very soon, while still more astonish- 

 ing is the early metamorphosis of the undersized larvae in cool 

 well-sprayed water of the fountain. The well-nigh simultaneous 

 metamorphosis of these larva: so soon after the beginning of these 

 experiments indicates that the chief cause of metamorphosis was 

 alike operative in all eases ; what this case was will become obvi- 

 ous later in the discussion. In other instances I have had larvae 

 prove much more resistent to metamorphosis when kept partially 

 or entirely out of water. I will relate one, which is interesting 

 because it was a semi-natural experiment and, in part, on a large 



Around the sloping cement sides of a large artificial reservoir 

 frost had raised a strip of plastering, perhaps a yard in width, 

 leaving a crevice an inch or more in depth below it. Until mid- 

 summer this crevice had been several feet below water, and here 

 about two hundred larva? had formed the habit of concealment, 

 their abraded back fins telling plainly that their occupancy of the 

 crevice had not been temporary. When these had reached a 

 length of ten to thirteen centimetres the water in the reservoir 

 was slowly reduced in depth, during a week or more, until, at 

 first portions, and then the whole of the crevice was above the 



