12 THE ALGAE 



began to query the unwieldy assemblages into which algae were 

 then grouped. Dillenius in 1741 subdivided the group Conferva 

 and Stackhouse in 1796 expressed his doubts about the assemblage 

 of forms which Linnaeus had placed in the genus Fucus. Until the 

 development of the microscope in the middle of the seventeenth 

 century, algae were regarded as lacking sexuaHty. Even so, it was 

 more titan fifty years after the introduction of the microscope be- 

 fore R. Reaumour described the sex organs o^ Fucus, and another 

 century elapsed before Turner, the author of the four great volimies 

 on the Fuci, described fertilization in Fucus. 



Towards the end of the eighteenth century, the burning of 

 seaweed for the extraction of soda was reaching considerable 

 proportions in France and was extending to Scotland, though 

 here it did not reach its heyday tmtil some way into the nineteenth 



century. 



The beginning of the nineteenth century witnessed the appear- 

 ance of Dillwyn's classical work on the Confervae. He lacked the 

 courage to segregate the various entities even though his writings 

 suggest he felt there was a need for division. It was also at this time 

 that Vaucher pubHshed his Histoire Confervae d'eau douce, which 

 represented a milestone, in that life history studies were first used 

 as a basis for taxonomy. In this work confirmation was given of the 

 reproductive process in Spirogyra. 



The early years of the nineteenth century were distinguished by 

 many great algologists. Not only were there Dillwyn and Vaucher, 

 but also Roth, who named and described the genera Hydrodictyon 

 (p. 44), Batrachospermum (p. 228) and Rtvularia-{p. 290). There were 

 numerous workers in the marine algae, and actually the knowledge 

 of these increased more rapidly than that of the fresh water algae. 

 Between 1805 and 1816 Lamouroux described many new genera, 

 including Laminaria (p. 172) and many of the tropical Chlorophy- 

 ceae. In Great Britain and on the Continent marine algae were 

 studied and described by Lyngbye, Bory and Greville, the last 

 named first describing the well-known genera Polysiphonia (p. 249) 

 and Rhodymenia (p. 246). In Sweden, C. Agardh established the 

 importance of the cystocarp in Rhodophycean taxonomy and 

 erected the divisions Diatomaceae, Nostochineae, Confervoideae, 

 Ulvaceae, Florideae and Fucoideae. The Nostochineae included 

 many Myxophyceae and the Confervoideae comprised the fila- 

 mentous green algae. He was followed by J. Agardh, his son, who 



