ZOOLOGY. 335 



from which start in every direction irregular filaments formed of the 

 same substance. These filaments, which are eminently contractile, 

 ramify and run into each other, forming a sort of woof, and always 

 ending at the enveloping membrane, the inside of which thus appears 

 lined with a very close network. To facilitate his observations M. 

 Quatrefages isolated the animalcules by straining the water containing 

 them through a towel. The brilliant noctilucs remained in the towel, 

 and were thus obtained in any desirable quantities for the purposes of 

 his experiments. The water having passed through the towel was to- 

 tally deprived of its luminous quality, which was regained in its origi- 

 nal degree upon replacing in it the animalcules which had been sepa- 

 rated. For more convenient experiment, the animalcules were placed 

 in a glass tube. On shaking the tube they became luminous. Upon 

 applying to them a glass magnifying six or eight times, it was easily 

 seen that, with the greater number the phosphorescence was only par- 

 tial, appearing and disappearing successively upon several points of the 

 body, while in other cases the whole body was luminous. With a mi- 

 croscope of increased power these facts became still more evident. 

 Numerous brilliant points became visible, appearing and disappearing 

 upon a luminous field. Apply now a very high magnifying power, 

 and the brilliant points are multiplied in the same proportion. The lu- 

 minous field disappears, and is proved to have been composed of an in- 

 finite multitude of very small lights. The phosphorescent parts of the 

 animalcule, says M. Quatrefages, may be considered as nebulae, which 

 the microscope of sufficient power resolves into separate stars, only the 

 stars, instead of being fixed, are so many instantly appearing and dis- 

 appearing lights. Several interesting experiments exhibited the effects 

 of an elevated temperature upon the noctilucs. At 25 Centigrade the 

 phosphorescence began to manifest itself, and continued to do so with 

 more and more brilliancy until the temperature reached 40 C. when 

 the light became extinct. The effect of many of the gases was then 

 observed. Chlorine was the only one which had the power to provoke 

 the emission of light in a considerable degree, without the aid of agita- 

 tion. The light emitted under its action was very brilliant, but soon 

 ceased, and it was found impossible to renew it. Paris Correspond- 

 ent of the National Intelligencer. 



NEST-BUILDING FISHES. 



AT the meeting of the American Association at New Haven, Prof. 

 Agassiz made an interesting communication on the " care which cer- 

 tain fishes take of their young." After referring to the general disbe- 

 lief with which stories of fishes taking care of their young have been re- 

 ceived, he stated that recently, while engaged in collecting insects 

 along the shores of Lake Sebago, in Maine, he was led to observe the 

 actions of a couple of cat-fish, which at his approach left the shore 

 suddenly and returned to the deeper water. This movement being 

 several times repeated, he was led to a closer observation. The pecu- 

 liar black appearance of the place which the fishes had left first at- 

 tracted his particular attention. Examining more closely, a nest was 



