PREFACE. XXV 



colour, the vesicle at the same time becoming indistinct, 

 while the remainder of the contents became coarsely 

 granulated, (through the formation of oil?). The .plants 

 have remained in this state ever since, not altering even 

 when the pools were refilled by rain. The resting, but 

 still green condition, seemed to me to correspond to 

 Protococcus Felisii, Kiitz., that which had turned red 

 through desiccation, to Pr. Orsinii, Kiitz. t at least, ac- 

 cording to the specimens sent to me by De Brebisson as 

 a small variety of that species. 



Herewith, I deliver these pages to the Fathers of our 

 High School, my honoured colleagues, with the petition 

 for a friendly reception, as a memorial of the efforts and 

 expansions in Science and in Life, we have shared in an 

 eventful 'year ; I deliver it to the Academic Youth, in 

 the hope that they may find therein the threads which 

 connect the separate fragments of knowledge into a 

 whole, and that the perception of this connection may 

 encourage them to follow, with double zeal, undistracted, 

 through good and evil times, the study of the material 

 so abundant in all branches of science, and thus to enter 

 more and more into the sacred workshops, in which are 

 hewn the stones for building the great Dome of human 

 knowledge. To the wider scientific public, lastly, I 

 deliver these pages, with the consciousness of having 

 therein published many results of conscientious research 

 which will find their place in the building of Science, 

 even if the connection in which I have here sought to 

 place them, should shape itself very differently in a 

 future, higher stage of development of Natural History. 



DR. A. BRAUN. 



FREIBURG, BRIESGAU; May, 1850 



