164 S. STILLMAN BERRY. 



a foot. . . . While the animal is living these spots are trans- 

 parent. 



"Again there are hundreds of other small spots all over the 

 body. . . . When seen in daylight they appear to be small 

 black spots, but in the night all these spots shine with a brilliant 

 light like that of the stars in heaven. . . . When these spots 

 (while the hotaru-ika is alive) are viewed under the microscope, 

 they are very interesting. When the animal is about to produce 

 the light, the membranes [chromatophores] covering the spots 

 will concentrate and remove themselves, thus opening a way for 

 the light. The light is so brilliant that it seems like a sunbeam 

 shot through a tiny hole in a window curtain. Again when the 

 hotaru-ika wishes to shut off the light, the membranes will 

 expand and cover the spots. . . ." 



In the following year Meyer (:o6) described briefly the photo- 

 genic activity of the myopsid, Heteroteuthis dispar (Riippell), 

 similar observations having been made some time previously 

 by Lo Bianco, but never published. Meyer found that in the 

 case of the specimen observed by him at the Naples Zoological 

 Station he "could in the dark room easily locate the position of 

 the photophore through the transparent mantle, lying on the 

 ventral surface just behind the anus." He further found that 

 when the animal was irritated, "it shot rapidly through the 

 water, and spurted through its funnel a luminous secretion which 

 floated in the water as separate globules, these being drawn out 

 by the currents into shining threads, a pyrotechnic display 

 (Feuerwerk) which he was able to repeat many times. The light 

 of the secretion and of the light organ itself had the same pale 

 greenish hue which we observe with our glow-worms." Meyer 

 further reports the discovery by one of his colleagues, Marchand, 

 of somewhat similar photogenic properties in Sepiola, except 

 that in this genus "the luminous secretion is not discharged into 

 the water but remains on the surface of the gland. Furthermore, 

 Sepiola only shines if it be very powerfully stimulated, as when, 

 for instance, the mantle is cut open." From the foregoing it is at 

 once evident that in both these myopsid genera the mechanism 

 of light production is very different from that of any of the other 

 forms studied, and this conclusion is borne out by the anatomical 



