284 E. NEWTON HARVEY. 



The light of Bolina comes from cells along the swimming plates. 

 According to Dahlgren (3), the luminous cells form a layer over 

 the testis and ovary, along the water vascular canals. In the 

 living animal I was unable to make out any yellow cells in this 

 region, comparable to the yellow masses of sEquorea or Mitrocoma. 



The light is of the same bluish-green color as the medusae, but 

 too faint and evanescent for a study of its spectrum. 



Bolina is an exceedingly fragile ctenophore and contains much 

 water and relatively little luminous material. The animals also 

 appear to be easily fatigued and lose somewhat their power to 

 luminesce on frequent agitation. Portions of the swimming 

 plate tissue placed on a glass slide, as much of the water drained 

 away as possible, and dried over CaCl 2 in the dark do not give 

 light on again moistening with water. This is probably to be 

 explained by the small amount of photogenic material present. 



If Bolinas are pressed through four layers of cheesecloth there 

 is obtained a luminescent solution which rather readily loses its 

 power of luminescence. It again gives light on vigorous agitation 

 or addition of cytolytic substances. It behaves as the extracts 

 of medusas and pennatulids. If fresh water is added, we have 

 the appearance of dots of light just as in these extracts. The 

 existence of luciferin and luciferase also cannot be demonstrated 

 and extracts of Bolina give no light with Cypridina luciferin nor 

 do heated extracts of Bolina give light with Cypridina luciferase. 



Since the observations of Allman (4) it has been known that 

 ctenophores would not produce light in the daytime. Peters (5) 

 made quite a study of this in Mnemiopsis and found that me- 

 chanical stimulation accelerates the appearance of luminescence 

 in darkness after previous exposure to light. The inhibition of 

 luminescence is roughly inversely proportional to the intensity 

 of the light which has previously illuminated them. 



Bolina shows marked inhibition of luminescence as a result of 

 previous illumination. Animals brought into a dark room from 

 direct sunlight about 10 A.M. gave no light whatever on stimu- 

 lation immediately or after five minutes, gave some light on 

 stimulation after ten minutes, and a good luminescence after 

 one half hour in the dark. The question at once arises as to 

 the cause of this behavior. Are the cells incapable of being 



