430 NOTES. 



I have by this process reduced to sterility for two whole years eight 

 old Axolotls, which had previously produced seven generations of young 

 ones ; when I replaced them in a large aquarium with running water, 

 sand, pebbles, and plants, in fifty hours they began to deposit eggs again 

 and produced from 900 to 1,000, of which at least 700 developed. This 

 in no way depends on the season of the year ,> at least three broods of 

 eggs can be obtained from the same female in one year. But the experi- 

 ment is apt to be rather a dangerous one, for the males not unfrequently 

 perish if the sexual processes are interrupted too soon. 



Note kl,page 126. To these larva-forms belongs the much-talked- 

 of Axolotl, whose capability of becoming under certain circumstances 

 a gill-less land-animal Amblystoma has been most undeservedly 

 celebrated as a perfectly marvellous phenomenon. It was assumed 

 that in Mexico, its native home, it never underwent any such transfor- 

 mation. But this is incorrect, for in the museum at Vienna there are 

 specimens of Amblystoma and of Axolotl which were collected at the 

 same time in the lake of Mexico. I owe this observation to my friend 

 Steindachner. The Axolotl of Lake Como, by the Central Pacific Kail- 

 way on the summit of the Rocky Mountains, according to Mr. Carlin, 

 always is transformed into Amblystoma it is Amblystoma mavortinm. 

 But the effects of an insufficient body of water, which is said by Weiss- 

 mann to cause the transformation of the Mexican Axolotl, cannot occa- 

 sion it in that of the Rocky Mountains, for it takes place in the water ; 

 and the Amblystoma, so long as they are little, actually live exclusively 

 in the water, as I know by my own experience. A young Amblystoma, 

 which I kept alive for a long time, never went out of the water of its 

 own free will, while one nearly twice as large lives entirely on land 

 and only takes a bath now and then. It always goes into the watev 

 when the temperature of the air in the cellar, in which my aquaria 

 stand, falls below that of the water down to about 6 or 8 C. 



Note 48,paf/e 129. Brauer's researches on the Phyllopoda contain a 

 mass of valuable observations on this point, which I will here collect 

 and reproduce for the sake of their wide general interest ; unfortunately 

 they cannot be tabulated. 



In all the species of Branchipus, e.g. CMroccphalus Braueri, which 

 first appear in early spring in pools of snow-water, a rapid rise of tem- 

 perature from the freezing-point is the first and chief condition of de- 

 velopment. These species perish at a temperature of '19C. At a suitable 

 temperature about 10C. ? the development of Chirocephalus from the 

 egg to sexual maturity takes only twelve days. 



Freezing the soil acts upon Apiis cancriformis, SrancJiijms stagnates, 

 and B. torvicornis, in the same way as desiccation, and in warm spring 

 days theydevelope in snow- water pools just as quickly as at midsummer 

 in warm rain-water pools. 



Eggs of Lepidurus productu* kept in damp earth from At>ril till 



