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SCIENCE 



[N. S. Vol. XLV. No. 1157 



point of view than from the standpoint of 

 geographical distribution in relation to 

 definite factors controlling it. 



The idea of geography as applied to plant 

 life, while present in indefinite form in the 

 treatises of the Greek period, came as a 

 revolutionary idea to the German Fathers 

 and their immediate successors. It was 

 Alexander von Humboldt, however, who, 

 early in the nineteenth century, gave the 

 first real impulse to the idea of the study 

 of the geography of plants (1805) and the 

 climatic conditions, climatic zones and alti- 

 tudinal zones which are to be associated 

 with, and to be taken account of in connec- 

 tion with it. It was J. V. Lamourous, how- 

 ever, who first formulated the outline of 

 topics connected with the distribution of 

 "Hydrophytes" (marine algse) in 1825 

 and 1826. Lamouroux had for his models 

 the works of von Humboldt, A. P. De Can- 

 dolle and Robert Brown on "Aerophytes." 

 It is of interest to notice the topics brought 

 forward by Lamouroux. In the first place, 

 the basis for his study, as he states, con- 

 sists of some 1,200 species of his own collec- 

 tions and those of the various botanists of 

 Paris, and including specimens collected in 

 many voyages to distant parts of the world. 

 He touches upon species which are, in a 

 sense, cosmopolitan and speaks of the 

 Ulvaceje or sea lettuce family, as being dis- 

 tributed from the poles to the tropics. 

 This is particularly in connection with the 

 temperature factor and he remarks that 

 the number of species is greater in the tem- 

 perate zones than in the very cold or very 

 warm zones. In treating of the distribution 

 of families, he makes the point that be- 

 cause of the configuration of coast lines, 

 their distribution from a center is linear 

 rather than radiating as in land plants. 

 He mentions seasonal temperature effects in 

 that the period of higher temperature in 

 any locality shows the greater number of 

 species. He also suggests that possibly the 



depth relation to distribution is the same 

 as the altitudinal relation to land floras and 

 that there may possibly be expected an 

 arctic or frigid marine flora in the depths 

 of tropical waters, as a frigid land flora is 

 found on high peaks in warm zones. 

 Lamouroux takes up the influence of light, 

 of the aeration of the water and of the 

 plant exposed more or less often and more 

 or less completely by the ebb and flow of 

 the tides. The substratum receives some 

 attention from Lamouroux and also a con- 

 siderable attention is given to the distribu- 

 tion of the particular divisions and fam- 

 ilies. Altogether Lamouroux has treated 

 of a considerable number of facts and fac- 

 tors underlying even the more modern con- 

 sideration of the subject. Greville (1830) 

 and W. H. Harvey (1849, 1851), as has al- 

 ready been stated, have followed Lamou- 

 roux and have treated of the geographical 

 relationships of the various floras, but 

 chiefly from the point of view of floristies. 

 Lamouroux and Harvey laid the chief em- 

 phasis on general climatic factors, of which 

 temperature is by far of widest effect and 

 importance, and this view was followed by 

 the later writers, who associated factors 

 with their floristic treatment. A new im- 

 petus was given the study of climatic dis- 

 tribution by Kjellmann's various papers, 

 particularly by "The Algte of the Arctic 

 Sea" and the later subdivisions of the 

 Polar Sea. The discussion of the marine 

 floras of the North Atlantic at the hands of 

 Reinke, Simmons, Boergesen and Jonsson 

 simply emphasizes the importance of this 

 climatic factor or sets of factors. 



Before leaving this more general treat- 

 ment, it may be well to speak of Piccone's 

 work (1883) as the only general treatise, 

 other than that of Lamouroux, on the geo- 

 graphical distribution of the marine algee. 

 Piccone treats of the general features of an 

 algal flora and the general conditions, such 

 as the substratum, both as to physical and 



