On the Seiches of the Lake of Geneva. 305 



that they are subjected to unequal pressures from different atmo- 

 spheric strata. 



Here, then, I finish the explanation of the singular pheno- 

 menon of the seiches. Subsequent observations will either de- 

 stroy, confirm, or perhaps modify, the causes which I have as- 

 signed for them ; but the more I reflect upon them, the more 

 do I find it difficult to conceive any others which can furnish 

 so satisfactory a solution of the different appearances which they 

 present. I should certainly have wished to have examined with 

 greater care the several lakes of higher Italy, as also Lucerne and 

 Constance, which so much resemble Geneva ; and I would ven- 

 ture to solicit travellers, who may have favourable opportuni- 

 ties, to examine the subject, and so to correct and to confirm the 

 solution which I have ventured to propose. 



Observations on the Origin of MonMiness. By M. Dutrochet, 

 Member of the Institute. 



Water, which holds organic substances in solution, very fre- 

 quently developes living beings, viz. the infusores, which be- 

 long sometimes to the animal and sometimes to the vegetable 

 kingdoms. These substances, which have been regarded by 

 certain naturalists as the product of spontaneous generation, 

 ought to be considered, with greater propriety, as owing their 

 appearance to the development of certain invisible germs which 

 are scattered throughout nature with profusion, and which only 

 require favouring conditions to assume their being, and to de- 

 velope themselves. We may place among the vegetable in- 

 fusores that kind of white byssits which is composed of minute 

 branching threads, sometimes articulated, and sometimes not, 

 which frequently exhibits itself in water, holding various or- 

 ganic substances in solution. It is to this vegetable production 

 that the observations made by M. Amici refer, and which are 

 expounded in his memoir entitled Observations stir rjccroisse- 

 ment des Vegetaux* M. Amici having observed, in those little 

 wounds by which the vine, in spring-time, pours out an abundant 

 sap, a kind of yellowish byssus, examined this substance with 



• Annales des Sciences Nalurelles, 1. xxi, p. 92. 



