--------------+------------+-------------+---------------+------------- |_Asterias_♂ | _Asterina_♂ |_Franciscanus_♂|_Purpuratus_♂ | | | | --------------+------------+-------------+---------------+------------- _Asterias_ |_Immediately|No |Moderately |Slight effect ♀ (immature) | very | activation. | active. | in immediate | motile._ | | | contact with | | | | egg. | | | | _Asterina_ | Not motile.|_Violent |_Violent |Slight effect ♀ (immature) | | activity._ | activity._ | only near | | | | the egg. | | | | _Franciscanus_|Slightly |No motility. |_Immediately |_Immediately ♀ (mature) | motile. | | active._ | active._ | | | | | | | | _Purpuratus_ |Slightly |Slight effect|_Immediately |_Immediately ♀ (mature) | motile | in immediate| active._ | active._ | after some | contact | | | time. | with eggs. | | --------------+------------+-------------+---------------+------------- The spermatozoa of starfish show a marked specificity inasmuch as they are strongly activated only by the eggs of their own species, although in this experiment these were immature, and to a slight degree only by the eggs of the sea urchin _purpuratus_. But it is also obvious that the specificity is far from exclusive since the immature eggs of _Asterina_ activate the sperm of the sea urchin _franciscanus_ as powerfully as is done by the mature eggs of the sea urchin _purpuratus_ and _franciscanus_. In studying these results the reader must keep in mind first that all these experiments were made in a NaCl solution and second that it requires a stronger influence to activate the spermatozoa of the starfish, which are not motile at first even in sea water, than the sea urchin spermatozoa which are from the first very active in such sea water, and which may therefore be considered as being at the threshold of activity in pure NaCl solution. Wasteneys and the writer (in experiments not yet published) did not succeed in demonstrating an activating effect of the eggs of various marine teleosts upon sperm of the same species.