Miscellaneous, 79 



the precipitate of protoxide of copper is probably caused in both 

 instances by the presence of glucose in the sap. 



The author has extended his investigations to some herbaceous 

 plants, and proposes communicating his results to the Academy of 

 Sciences very shortly. He mentions as one of them, that the spiral 

 fibres of the reticulated, annular and spiro-annular, and other similar 

 vessels also present in their interior a red precipitate, formed of 

 small flakes, of a blackish-brown colour when observed under a high 

 power, and apparently identical with that mentioned above. This 

 fact appears to confirm the views of M. Trecu) on the structure of 

 these fibres. — Comptes Rendus, June 1, 1863, p. 1048. 



The Mode of Development of the Marginal Tentacles in the free 

 Medusoids of some Hydroida. By A. Agassiz. 



M. Agassiz has investigated a point hitherto neglected in the deve- 

 lopment of the medusoids, namely, the mode of appearance of their 

 marginal tentacles. Each medusoid has really originally a limited 

 number of tentacles, which is subsequently increased by the succes- 

 sive appearance of several series of new tentacles. The series of 

 tentacles in these Acalephse may be compared to the cycles of septa 

 in the Zoantharian polypes ; and, in fact, their order of appearance 

 coincides in certain cases vnth that of the visceral chambers of the 

 polypes, although the exceptions to this rule are very numerous. 

 It is also to be observed that in the Zoantharia the number of 

 chambers of the first cycle is almost always six. In the Acalephs 

 the number of tentacles of the first series is, on the contrary, ex- 

 tremely variable. For a great number of genera M. Agassiz has 

 drawn up formulae showing the order of succession of the tentacles 

 of different series. 



Certain Acalephs are singular, such as the medusoids of some 

 TubularicB. That of Corymorpha pendula, for example, has only a 

 single tentacle of the first series. The tentacles of the second series 

 are two in number, and placed at the extremities of a diameter per- 

 pendicular to that corresponding with the tentacle of the first series. 

 The third series consists of a single tentacle, opposite to that of the 

 first series. — Proc. Boston Soc. Nat. Hist., August 1862; Bibl. 

 Univ., 1863; JBull. Scient., p. 161. 



On the Question whether Diatoms live on the Sea-bottom at great 

 Depths. By Wm. Stimpson, M.D. 



In a paper on the Diatomacese found in mud collected at great 

 depths from the bottom of the sea off the coast of Kamtschatka, in 

 soundings made by the North Pacific Expedition under Commander 

 Rodgers (Silliman's Journal, ser. 2. vol. xxi. p. 284), the late 

 lamented Professor Bailey made the following remark : — " The per- 

 fect condition of the organisms in these soundings, and the fact that 

 some of them retain their soft parts, indicate that they were very 



