viii PREFACE 



as a rude shock to some teachers to find that long-established 

 friends, e.g. Gonium, Vaucheria, have not been asterisked. The 

 present author believes that such types should have been omitted 

 from curricula years ago either because they do not convey any- 

 thing essentially new, or else because recent work has shown them 

 to be wholly unsuitable types for elementary students. Up to the 

 present, however, established tradition has kept them firmly 

 ensconced in their position, but whether they will be able to retain 

 it remains to be seen. It is suggested that third and fourth year 

 students should study additional types selected from among the 

 other species. Certain of the other chapters have also been marked 

 as suitable for the first and second year students. Several chapters 

 have been devoted to Ecology because the literature now available 

 in this branch of the subject ought to be made accessible to the 

 ordinary student. In these other chapters limits of space have 

 rendered it necessary to select the material, and it may be felt by 

 other teachers that some original work has been omitted that 

 perhaps might have been inserted. In a book of this type such a 

 feature is inevitable, and the author acknowledges that the choice of 

 material has been a personal affair and that it is, as such, open to 

 this criticism. There is a chapter on Physiology, Symbiosis and the 

 Soil Algae, and also one that is devoted to a surv^ey of reproduction 

 and evolution. Part of one chapter is devoted to a brief account of 

 the more important fossil types because it is essential that these 

 should be studied and compared with their living successors, and 

 also an acquaintance with these forms materially aids any discus- 

 sion on evolution. 



The algae are now divided into a number of groups, and whilst 

 it is essential that the student should know that these groups exist, 

 nevertheless, his attention should be concerned primarily with the 

 major divisions. For this reason most attention has been given to 

 the Chlorophyceae, Xanthophyceae, Cyanophyceae, Phaeophyceae, 

 and Rhodophyceae. This is perhaps somewhat indefensible, but 

 since the species which are normally encountered by the student 

 belong principally to these groups, I believe the procedure is 

 justified. 



In order that the student should not be burdened unduly, only 

 the more important papers have been provided in the references, 

 but even these are appended only for those who are especially 



