38 . HANDBOOK OF INVERTEBRATE ZOOLOGY. 



The most favorable time for all kinds of surface-collect- 

 ing is a calm evening, when the water is phosphores- 

 cent ; and in most localities, especially on low sandy 

 coasts, a greater variety of forms will be met with at high 

 water than at other times. 



After the bucket with its contents has been carried 

 home, a small quantity of the water should be dipped up 

 in a small beaker or a tumbler with smooth sides, and held 

 before a light for examination. The collection will proba- 

 bly be found to contain numbers of small rounded nearly 

 hemispherical transparent medusae, and these may be 

 picked out with a dipping-tube and preserved for examina- 

 tion in sm.'dl aquaria or beakers of fresh sea-water. 



Most of the points in this description may be made out 

 by the examination of living specimens, but they may be 

 preserved for winter work if necessary. The most satis- 

 factory method of preservation for microscopic examina- 

 tion is by the use of osmic acid. The specimens to be 

 preserved should be placed alive in a large watch-crystal 

 full of sea-water, and to this fifteen or twenty drops of one 

 per cent solution of osmic acid in distilled water should be 

 added. 



As soon as the specimen begins to turn dark, which will 

 be in five or ten minutes, pour off the water and fill the 

 watch-crystal with new sea-water, and pour this off in five 

 or ten minutes and renew once more. This should be 

 done several times to wash out all traces of the acid. The 

 specimen may then be strained in dilute picro-carmine 

 for about an hour, and it may then be preserved in a mix- 

 ture of equal parts of ninety-five per cent alcohol, sea- 

 water, and glycerine. If osmic acid cannot be procured, 

 satisfactory specimens can be preserved with picric acid. 

 The specimens should be placed in a flat-bottomed dish 



