EXPEIUMENTS IN STIMULATION. 41 



instance, however, happens to have been correct, as 

 he results of the following experiments will show. 



Having put two or three hundred Sarsifle into a 

 large bell-jar, I completely shut out the daylight 

 from the room in which the jar was placed. By 

 means of a dark lantern and a concentrating lens, 

 I then cast a beam of light through the water in 

 which the SarsijB were swimming. The effect upon 

 the latter was most decided. From all parts of the 

 bell-jar they crowded into the path of the beam, 

 and were most numerous at that side of the jar 

 which was nearest to the light. Indeed, close 

 against the glass they formed an almost solid mass, 

 which followed the light wherever it was moved. 

 The individuals composing this mass dashed them- 

 selves against the glass nearest the light with a 

 vigour and determination closely resembling the 

 behaviour of moths under similar circumstances. 

 There can thus be no doubt about Sarsia possessing 

 a visual sense. 



Anschauungen oline Weiteres auch auf die wirbellosen Thiere der 

 verscliiedenen Kirese zu iibertragea und bei diesen analoge 

 Sinnesempfindungen anzunehmen als wir sebst besitzen. . . 

 Noch weniger freilich als die von den meisten Autoren angenom- 

 mene Deutung der Randblaschen nnserer Medusen als Gehororgane 

 kann die von Agassiz und Fritz Miiller vertretene Ansicht befrie- 

 digen, dass dieselben Augen seien. . . . Alle diese Verhaltnisse 

 sind mit der Deutung der Concretion als 'Linse' und des sie 

 umschliessenden Sinnesganglion als ' Sehnerv * durchaus nnve- 

 reinbar." 



It may not be unnecessary to say that, although the simple 

 experiment above described effectually proves that the marginal 

 bodies have a visual function to subserve, we are not for this 

 reason justified in concluding that these are so far specialized as 

 organs of sight as to be precluded from ministering to any other 



