1 66 S. STILLMAN BERRY. 



examines them close at hand, shine like an electric illumination. 

 The color of the light is a beautiful clear blue. 



"As Watase writes, the arm organs in dead animals are en- 

 tirely surrounded by pigment cloaks and only when alive can 

 the animal retract these. The retraction of these cloaks takes 

 place very qu : ckly, and when they are retracted, the organ ap- 

 pears in daylight as a delicate dull-green colored body." 



In a paper which comprises a most notable contribution to 

 our knowledge of the ecology and habits of ten-armed cephalo- 

 pods, Sasaki (:i4, pp. 77-80) adds materially to the accounts of 

 his predecessors. Some of his observations are so pertinent to 

 some of the discussion which must follow later that they should 

 be quoted rather fully. Treating the three types of photophore to 

 be seen in Watasenia under separate headings, this author writes: 



"Brachial Organ. This is the largest organ, and when I made 

 observations in the fishing season, it was much more active in 

 phosphorescence than other organs. It is situated at the end 

 of each ventral arm, composed of 3 globules arranged in a 

 series. The globules are ovoid in shape and nearly equal in 

 size, but the middle one in the series is generally a little larger 

 than the others, the dimensions being 1.4 mm. long and about 

 I mm. broad. In fresh specimens they show a greenish cobalt 

 colour, and there are 2 or 3 layers of large brownish chroma- 

 tophores covering a part of the preceding substance. These 

 chromatophores are constantly contracting and expanding. 

 When they were observed at night on the living animals, they 

 were seen to discharge light in all directions much brighter 

 than any of Japanese fireflies. The color of the light is Prussian- 

 blue or tinged a little with purple, and the luminosity is strong 

 enough to outshine the other luminous organs. When the living 

 animal was placed on a glass plate, which was put directly on 

 the case of the dry plate of the photographic camera, and then 

 exposed for four seconds with the Lion's dry plate of the special 

 rapid no. 230, the light of this brachial organ was distinctly 

 taken on the dry plate, although those of other organs made no 

 impression. 



"Minute Organs Scattered on the Ventral Surface of the Whole 

 Body. There are numerous minute organs distributed on the 



