334 ANNUAL OF SCIENTIFIC DISCOVERY. 



pound group of individuals as the zoophyte. In some cases the plant 

 forms but a single leaf-bud, in others, where there is successive gem- 

 mation for a period, the number is gradually multiplied, and more or 

 less, according to the habit of the species. So among Polyps, there is 

 the simple compound Tubularia, Campanularia, and the like. After 

 the plant has sufficiently matured by the production and growth of its 

 number of leaf-buds, there is a new development, a flower-bud, con- 

 sisting of the same elements as the leaf-bud, but wholly unlike it in 

 general appearance, as much so as the Medusa is unlike the Polyp. 

 The flower-individual starts as a bulb from the leaf-individual, or the 

 group of leaf-individuals, and is analogous in every respect to the bulbs 

 from the Campanularia; and allied species ; and when it has fully ma- 

 tured it produces, like the Medusa, ovules or seeds, these seeds to 

 begin again the round of successive or alternating developments. 



Thus among plants the seeds produce leaf-individuals ; these yield 

 bulbs or buds becoming flower-individuals : and these produce seeds, 

 precisely as the egg produces Polyps, the Polyps bulbs that develop 

 into Medusa, and the Medusa eggs. 



When we follow out this subject minutely, we find the analogy com- 

 pletely sustained even in minor points of structure and growth. The 

 leaf-bud consists of leaves developed in a spiral order, and in the Polyp, 

 as some species show beyond doubt, the tentacles and corresponding 

 parts are spiral in development. The same spiral character is found in 

 the flower, but the volutions are so close as not to be distinguished 

 readily from circles. In the Medusa referred to, the regularly circular 

 form is far more neatly and perfectly developed than among Polyps. 

 The only point in which the analogy seems to fail is that the Medusa- 

 bud falls off before its full development, while this is not so with 

 plants. It. is obvious that this is unimportant in its bearing on this 

 subject. It is a consequence of the grand difference in the mode of 

 nutrition in the two kingdoms of nature ; for the plant-bud on separa- 

 tion loses its only means of nutriment. The law of alternating gener- 

 ation is therefore no limited principle, strange and anomalous, apply- 

 ing only to a few Radiata. It embraces under its scope the vegetable 

 kingdom, and it is but another instance of identity in the laws of 

 growth in the two great departments of life. American Association, 

 Silliman's Journal, by Prof. J. D. Dana. 



PHOSPHORESCENCE OF THE SEA. 



M. QUATREFAGES has recently read before the Academy of Sciences 

 an interesting memoir respecting the phosphorescence of the sea, in 

 which he communicates the result of observations and experiments up- 

 on the animalcules which are now universally recognized as producing 

 this phenomenon. His observations were made during a series of 

 years on the French Atlantic coast near Boulogne. He calls these an- 

 imalcules noctilucs, and describes them as of very simple yet curious 

 organization. The body is formed of a globular diaphanous membrane, 

 which is seen upon close inspection to be pierced with a very small 

 hole. Internally is remarked a small collection of granulous matter, 



