250 PROFESSOR PANCERI. 



matter is found, on the contrary, thrown back into the canals 

 of the latter. Thus it may be understood how Spallanzani, 

 entirely compressing in his hand the stem or the base (vessillo) 

 of a Penatulide, obtained at the extreme pore of the stem 

 (gambo) a luminous jet. In the same way may be explained 

 how Delle Chiaje has seen the bulb of a Funiculina shine like 

 a lighted brand. I have myself verified the case of the Funi- 

 culina, but the light arose from the phosphorescent substance 

 which was mixed in the milky serosity (sierochimo) of the 

 canals of the Polypidom, and which was seen by transparency 

 on account of the delicacy of the external tegument. I very 

 easily recognised this matter under the microscope. 



Professor Wagner, of the University of Kasan, told me he 

 had once seen at Naples a pale light issue from the stem of a 

 Pennatula, which would have much astonished me, after having 

 found special luminous organs, if I had not thought it was 

 identical with what I have cited above in connection with the 

 Funiculines. It always happens that the luminous matter 

 in one way or another is set in motion, either by a shock or, 

 it may be, by regular pressure exercised upon the rachis. 

 The light which may be created in the liquid substance to 

 which the stem of a Pennatula is reduced by decomposition 

 is due to the same photogenic matter which we have seen to 

 be the last to decompose. The physiological part of the 

 memoir commences by a chapter in which are mentioned the 

 different conditions in which a Pennatula may be found, upon 

 which one may study the phenomena of light. When these 

 zoophytes, living at the depth of forty to one hundred metres 

 and more, are dislodged from their deep dwellings and trans- 

 ported to an aquarium, they undergo such a change in the 

 pressure, the temperature, the saltness of the water, the 

 general conditions, and, above all, the narrowness of the 

 space, that little by little they swell prodigiously to double 

 their bulk. In this state, which was called hydropic, as also 

 in the tetanic state, to which the Pennatulee are subject 

 when they are subjected to repeated manipulation, or in yet 

 another state, which is that of exhaustion, the inevitable con- 

 sequence of a prolonged sojourn in an aquarium or of repeated 

 experiments, the tissues of a polypid are no longer endowed 

 with any conductability by excitation, and the polypes only 

 yield the light when they are directly and individually 

 stimulated. 



If> on the contrary, it happens that experiments are made 

 on individuals fresh from the sea, and, in consequence, not 

 yf t hydropic, or on others in whom hydropsy is already 

 diminished, or generally in others which are far from ex- 



