154 A. IT. IJEGINAT.D IirLLEK. 



seen to pass by an egg so as almost to touch it, apparently 

 without being in any way influenced by its presence. 

 Nothiug was seen which in any way reminded mo of tlie 

 chemota.ctic phenomena either of bacteria or of the sperma- 

 tozoa of ferns. 



It is undoubtedly true that the spermatozoa collect rapidly 

 in the gelatinous coat of an egg. This is, however, duo to 

 the fact that the spermatozoa which strike the outer surface 

 immediately bore into the interior. It will subsequently be 

 shown more fully that the phenomenon takes place equally 

 well when the jelly encloses (1) a ripe egg; (2) an egg not 

 having undergone maturation; and (-"i) an egg which has 

 been killed with osmic acid, and then washed. There is thus 

 not the slightest necessity to account for the collection of the 

 spermatozoa in the gelatinous coat by any chemotactic sub- 

 stance Avhich diffuses through the jelly into the sea-water, 

 and so attracts spermatozoa towards the egg. 



If a substance causing attraction is really excreted by the 

 eggs one should be able to collect it. On this assumption 

 the following experiments were made. 



A freshly obtained female Arbacia was cut open. Tlie 

 eggs, which were then extruded by the animal in dense 

 masses from the oviducts, were collected in about 100 c.c. sea- 

 water contained in a crystallising dish. As soon as the eggs 

 had settled to the bottom, for the purpose of washing them, 

 the water Avas nearly all removed by means of a pipette. 

 Another 100 c.c. was then added, and so much again removed 

 after the eggs had settled that tlie lattei-, very thickly placed 

 together, formed a layer in about 1 — 3 mm. of the sea-Avater. 

 Sufficient oxygen could thus b(^ obtained for respiration. 

 The eggs were left in the water fi'om two to twelve hours, 

 usually about six. At tlie end of this period the water was 

 filtered, and the eggs thus removed. Ca])illary glass tubes, 

 about 12 mm. long and O'l — ()•') mm. intei'ual diameter, and 

 closed at one end, were then half filled with the water by 

 means of an air-pump. I'he tubes were then introduced into a 

 Largo open di-op of sea-water, in which fresh, highly motile 



