35 



PROGRESS AND OUTSTANDING 

 ACHIEVEMENTS IN PHYCOLOGY 

 DURING THE PAST FIFTY YEARS 



George F. Papenjuss 



The fiftieth birthday of our Society marks a period during which significant 

 advances have been made in all branches of phycology. As it will be possible 

 in this paper to point to only a few of the landmarks, I shall confine myself 

 to important contributions to knowledge of the morphology of some of the 

 major groups of algae and to the effects that this new knowledge has had on 

 the classification of these plants. A fuller treatment of these topics, covering 

 all the groups of algae and the period 1753-1953 was recently published 

 (Papenfuss, 1955). 



CHLOROPHYCOPHYTA 



Hertwig in 1876, studying fertilization in a species of sea urchin, showed 

 for the first time that a significant feature of sexual reproduction is the fusion 

 of the gamete nuclei. A similar fusion of nuclei in plants was first observed 

 by Schmitz (1879) in Spirogyra, and Berthold (1881) saw it in the brown 

 alga Ectocarpus, shortly afterward. 



Following the stimulating postulate of Weismann (1887) that the doubling 

 of the chromatin mass at syngamy must be followed by a regulatory reduc- 

 ing process, many investigations were undertaken with the view of testing 

 this hypothesis and of determining the place in the life history where the re- 

 duction may occur. 



The first observations on meiosis in the green algae were made by Allen 

 (1905) in Coleochaete during the time that he was working in Strasburger's 

 laboratory. The life history of Coleochaete had previously been investigated 

 by Pringsheim (1860), who showed that the zygospore divides into a number 

 of cells, each of which produces a zoospore. Pringsheim and others regarded 

 this structure as the sporophyte of Coleochaete. Allen established, however, 



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