14 



Among the literature of this department of Biological 

 science during the past year, I would especially point out the 

 work of Strasburger, " Die Coniferen und Gnetaceen ;" these 

 plants as you are aware constituting the Gymnosperms, and 

 remarkable especially for the absence of an ovary, style and 

 stigma. In this work which is accompanied by a quarto 

 atlas of 26 plates, the author minutely describes their develop- 

 ment and morphology, mixed up with which however is 

 much theory of a fanciful nature, especially a genealogical 

 tree, tracing back the conifers to Cycadese, which in turn he 

 regards as derivatives of the extinct Lepidodendra, wtile the 

 three little genera of Gnetacese are set down as the origin of 

 Dicotyledons. 



In the Smithsonian Contributions is a valuable monograph 

 of the fresh water Algoe of North America, by Dr. H. C. 

 Wood, with 21 quarto plates. The species are described in 

 accordance with Rabenhorst's work, the Diatoms being 

 omitted, and I refer to it, as it may be of use to us here, 

 until we get some similar work on this department of our 

 own Flora. 



I would also set a high value on the labours of my friend 

 Mr. Carruthers on fossil plants ; the use of the microscope 

 by this competent observer, having cleared away much of the 

 obscurity which shrouded our knowledge of these extinct 

 plants, which but too frequently have come down to us, only 

 as fragments of skeletons infiltrated with extraneous mate- 

 rial ; the result has been a true interpretation of their struc- 

 ture and affinities, and in many cases the restoration of the 

 complete individual by the combination of two or more sup- 

 posed genera into a single species. 



The last point under this head to which I would call 

 attention, is a subject on which much has been written in 

 Continental journals, without the matter having been settled. 

 I allude to the extraordinary views propounded by Schwen- 



