SECT. 2] ORGANIC REGULATION OF PHYTOPLANKTON FERTILITY 199 



distress to the scientists of this laboratory which pioneered so much work in 

 marine biology. During 1930 Wilson experienced great difficulties in rearing 

 larvae of polychaetes in the local sea-water. Later it became clear through the 

 work of Russell, Cooper, Armstrong and Harvey, at the Marine Biological 

 Association at Plymouth, that the local planktonic and hydrographic conditions 

 had changed. This prompted Wilson to analyze the biological properties of the 

 new water-masses (typified by the indicator species Sagitta setosa) and compare 

 it with the S. elegans water which previously surrounded Plymouth. Employing 

 Echinus esculentus, Ophelia bicornis and Sabellaria alveolata as bioassay or- 

 ganisms, he found the two types of water remarkably different : in setosa 

 water, eggs and larvae of the sea urchin and worms developed abnormally ; in 

 elegans water, they grew normally (Wilson, 1951 ; Wilson and Armstrong, 

 1952). In nature elegans water supports good growth of phytoplankton and 

 zooplankton. Addition of antibiotics, filter-sterilization, variations in pH, 

 addition of B12, ascorbic acid, or a metal chelating agent (EDTA), and of 

 supernatants of thick cultures of diatoms and flagellates all did little to im- 

 prove bad waters for the above organisms (Wilson and Armstrong, 1954, 1958). 

 Experiments in which eggs were allowed to develop in a mixture of the two 

 types of water suggested that it is the presence in good water of something 

 beneficial rather than the presence in bad water of something harmful which 

 makes the difference. Extracts with activated carbon and acetone of the bad 

 and good waters gave confusing results : neither supported normal growth. 

 Wilson attributed this to the properties of the samples of waters employed for 

 extraction : both water samples, including the good water, supported abnormal 

 growth. 



The original observations of DeValera (1940) that superficial waters of the 

 tidal Fucus-Ascophyllum zone permit the normal development from zygotes of 

 Enteromorpha, while the water of 30-m depth allows only stunted and slow 

 growth, resulted in a luckier chase. H. Kylin (1941, 1943, 1946) employed 

 germinating zygotes of the seaweeds Enteromorpha and Ulva as bioassay 

 organisms, and counted the number of cells produced by the germinating 

 filament at a fixed time in various enrichments of the infertile deep water : he 

 found that these waters are poor in NO3, PO4, Fe and Mn. A. Kylin (1943, 1945). 

 with the same technique, obtained normal growth with super-added Zn, Mn, 

 Fe and Co, while Ni, Al and Cd were inert. H. Kylin (1946) concluded that 

 fertility of the inshore waters for seaweeds is due to their relative richness in 

 X. P. and trace metals, and that these important elements for plant growth 

 diminish with depth and distance from the shore : waters of 70-m depth are 

 poorer in trace metals than the 30-m depth waters. The success of the two 

 Kylins and the lack of results of Wilson reflect the status of the knowledge of 

 the two fields of nutrition ; much was known of algal and plant nutrition and 

 Kylin could make a more educated guess as to what might be lacking in poor 

 waters. Wilson faced the utter unknown ; very little, if anything is known about 

 the physiology of sea urchins and marine worms ; any of a thousand known 

 substances could be responsible. 



