On the Phosphorescence of some Metrine Invertebrata. 15 



cuius is seen adherent to the opposite side, and the axis of the 

 style is seen inclining to the ventral tuberosity. 



Fig. 4. The same more magnitied, showing the cellular somewhat circuitous 

 canal ^^hich extends from a, the ventral tuberositj, to the canty of 

 the ovarj' j the external and internal openings being closed only by 

 a thin layer of cellular tissue : the axis of the short stjle, together 

 with its termination in the cavity of the carpel external to the 

 funiculus, and also the fibres of the funiculus, are here distinctly 

 seen. 



Fig. 5. An ovarj' of Ceratophyllum demersum in longitudinal section. 



Fig. 6. A carpel of Hydropeltis purpurea in longitudinal section : a, the 

 ventral side which is turned towards the axis of the polycai-pous 

 ovarj-. 



Fig. 7. A carpel of Cabomba aqtiatica, the dorsum having been removed. 

 Two ovules are seen attached to the lateral fibres, which are con- 

 tinued upwards and meeting at the ventral suture become con- 

 tinuous ; at this part the third ovule is seen attached. 



Fig. 8. An ovar}' of Arum maculatum in longitudinal section : a, the ante- 

 rior side. 



Fig. 9. An ovar\- of Sparganium ramosum in which the dorsal portion of 

 the stigma had become fissured ; when dicarpous, which fre- 

 quently happens, the stigmatic surfaces of the two carpels are 

 turned towards each other. 



Fig. 10. Cryptocoryne ciliata : a, the fissured stigma. (Griffith.) 



VI. — On the Phosphorescence of some Marine Invertebrata, 

 By M. A. De Quatrefages*. 



I. Historical review of the Subject. 



1. Causes of phosphorescence. — It is well known that the 

 waters of the sea, in some latitudes and under certain circum- 

 stances, are phosphorescent, producing a light more or less bril- 

 liant. This remarkable phsenomenon has always attracted the 

 attention of travellers, and various have been the explanations 

 they have offered. Without going here into useless detail, we 

 will first mention those hypotheses which are now completely set 

 aside, before dwelling on better-founded opinions. 



Ancient navigators seem to have indicated a resemblance be- 

 tween the light produced on the surface of the water and that 

 which is due to atmospheric phsenomena, by designating the 

 former " meteors of the sea." Something of this idea is evident 

 even in the writings of learned men, who endeavoured to explain 

 this phosphorescence solely by physical or chemical causes. Thus 

 Nollet could see in it only a simple modification of electrical 

 phsenomena. Bajon, in his memoirs on the Histoiy of Cayenne, 

 regards this light as due to the electricity of the waves, deve- 



* From the Annales dea Sciences Naturelles, vol. liv. 3rd series, as in- 

 serted in Silliman's American Journal of Science for March, 1853. 



