100 THE BIOLOGY OF THE ANIMAL 



They may be stained in. borax carmine either before or 

 after cutting, or left unstained as desired. 



The larval forms of the starfish may be obtained 

 along the New England coast from June to September, 

 by skimming, or they may be raised from the eggs. 

 Very small starfishes, suitable for study with the micro- 

 scope, may be found attached to eel-grass during the 

 summer. If a number of starfishes be caught during 

 the time mentioned and be kept for a few hours in a 

 pail of sea-water, some of them will probably be found 

 to be discharging eggs or sperm. The former may be 

 distinguished by their pinkish color ; the latter is white. 

 About a teaspoonful of the eggs may be thoroughly 

 mixed with a few drops of sperm in a tumblerful of 

 sea-water and set in a cool place. By means of a pi- 

 pette the water should be changed three or four times 

 a day and aerated frequently. Some of the eggs may 

 be taken out from time to time to watch the process of 

 segmentation, or this process may be studied in eggs 

 fertilized on the slide. Eggs in various stages of seg- 

 mentation may be taken from the tumbler at intervals, 

 and preserved for further study after treatment as fol- 

 lows : Place the eggs for ten or fifteen minutes in Klei- 

 nenberg's picro-sulphuric acid (undiluted); transfer to 

 thirty-five per cent., then to fifty per cent., alcohol each 

 for an hour ; then place them in seventy per cent, alco- 

 hol, and change the latter as often as it becomes dis- 

 colored. Such specimens may be stained in Delafield's 

 hsematoxylin. Spermatozoa, ^nd eggs showing the for- 

 mation of the polar globules, seldom preserve satisfac- 

 torily. Another method of obtaining eggs and sperm 

 is to cut open the body, remove the egg and sperm- 

 glands, and chop up the glands together in a watch-glass 

 of water, or chop them separately and mis them after- 



