190 



INTRODUCTION TO CRYPTOGAMIC BOTANY. 



et Ordines, Algarum, 1851, places Spongiocarpeas in his order 

 Chondriece, associating it with Loinentaria and Laurencia, 



But the spongy fruit of the one 



though in a different tribe. 



Fig. 46. 



a. Thin slice of Polyides rotundus, Grev., showing the wedge-shaped 

 spores radiating in every direction, magnified. One nucleus is divided 

 through the centre ; a portion only of a second is seen beneath. 



6. Tetrasporea young and old, magnified. Both from Mrs. Griffiths. 



c. Thin slice of Furcellaria fastigiata, Lyngb., magnified, showing a 

 nucleus with the dividing spores. Prom a specimen communicated by 

 Lenormand.* 



d. One of the large cells, to show its granular contents, which are of 

 a beautiful violet, when treated with the compound iodide of potassium 

 and sulphuric acid. The contents of the spores, on the contrary, be- 

 come yellowish brown. 



e. Tetraspore, after Harvey. All more or less magnified. 



filled with nuclei, can scarcely be compared with the naked 

 conceptacles of Chondria, with their single nucleus and basal 

 spores. Dr. Harvey's notion, however, of the fruit does not accord 

 with my observations. The placenta arises either distinctly 



* Unfortunately, I can find no fruit in specimens from Mrs. Griffith,"., 

 supposed to have perfect spores, and cannot, therefore, compare what I 

 find in Lenormand's specimen with the plant as examined by Harvey. 

 The differences, however, are of little importance. One great distinc- 

 tion in the structure of Polyides and Furcellaria is, that in the latter 

 so many horizontal cells traverse the medullary fibres, as represented 

 in the figure. The external cells vary extremely in length. 



