THE MICROSCOPE IN HISTOLOGY AND BOTANY. 139 



the biologist. "The plan of the present work permits us 

 only to indicate a few particulars, the details of which 

 would form a volume of considerable size. 



The Algae are divided into three orders: I. Rhodosper- 

 meoe or Florida (Red-spared Algce). Marine plants, with 

 a leaf-like or filamentous rose-red or purple thallus. II. 

 Melanosporece or Fucoidece (Dark-spored Algae). Marine. 

 Thallus leaf-like, shrubby, cord-like, or filamentous, of 

 olive-green or brown color. III. Chlorosporece or Confer- 

 voidece (Green-spored Algce). Plants marine or fresh water, 

 or growing on damp surfaces. Thallus filamentous, rarely 

 leaf-like, pulverulent, or gelatinous. These have been 

 subdivided into families, viz. : 



I. Rhodospermeoe. 1. Rhodomelaceae. 2. Laurenciaceae. 

 3. Corallinaceae. 4. Delesseriaceae. 5. Rhodymeniaceae. 

 6. Cryptonemiaceae. 7. Ceramiaceae. 8. Porphyraceae. 



II. Melanosporece. 1. Fucaceae. 2. Dictyotaceae. 3. 

 Cutleriaceae. 4. Laminariaeeae. 5. Dictyosiphonaceae. 6. 

 Punctariacese. 7. Sporochnacese. 8. Chordariacese. 9. 

 Myrionemace83. 10. Ectocarpaceae. 



III. Chlorosporece. 1. Lemaneese. 2. Batrachospermeea. 

 3. Cho3tophorace8e. 4. Confervace^e. 5. Zygnemaceae. 

 6. (Edogoniacese. 7. Siphonaceee. 8. Oscillatoriaceae. 9. 

 Xostochacese. 10. Ulvaceae. 11. Palmellaceea. 12. Des- 

 midiaceae. 13. Diatomacese. 14. Yolvocineea. 



For fuller information, we refer to the Micrographic 

 Dictionary by Griffith and Henfrey. 



In the family of Palmellacece we find the simplest forms 

 of vegetation in the form of a powdery layer of cells, or a 

 slimy film, or a membranous frond. The green mould on 

 damp walls and the red snow of alpine regions are exam- 

 ples. 



In the green slime on damp stones, etc., is found the 

 Pcdmoglcea macrococca. The microscope shows it to con- 

 sist of cells containing chlorophyll, surrounded by a ge- 

 latinous envelope. These cells multiply by self-division. 



