128 Jt 100 YEARS EXPLORING LIFE, 1888-1988 



research programs addresses the basic problems and uses techniques 

 developed by MBL scientists over the course of a century. 



Rachel Fink provides an excellent example of blending the old and the 

 new with her work on development of toadfish eggs: she became intrigued 

 by the eggs after reading about the work of Cornelia Clapp a century ago. 

 These eggs adhere to a solid surface, which makes them useful for various 

 sorts of experimental work that tests the relative effects of internal and 

 external changes in directing development. Clapp had looked at the impor- 

 tance of gravity for determining the embryonic axis, for example. Fink 

 decided to study these eggs with current techniques to explore twentieth- 

 century problems. Her work demonstrates the MBL tradition in going 

 beyond the earlier work, to combine tradition and innovation in a progres- 

 sive, productive way. 



Traditional views certainly held that environmental factors can exert a 

 major influence in development, just as internal inherited material does. 

 Researchers such as Jacques Loeb, who emphasized the physiological and 

 physicochemical processes of development, began the continued call for a 

 stronger epigenetic and environmentalist position. To Loeb, it seemed that 

 the female did not even require any male input. The egg did not really need 

 any sperm to get it going along its proper developmental pathway; a simple 

 change of salt concentration in the seawater could do the trick by initiating 

 artificial parthenogenesis. Chemical environmental factors gained top bill- 

 ing with him and his entourage of graduate students and assistants well into 

 this century. 



Morgan agreed with this physicochemical orientation, as he embarked 

 on studies of regeneration and sex determination right up until 1910. Then 

 his first work in genetics abruptly confronted him with problems of heredity 

 rather than of physiology and development. Others have carried on the 

 physiological programs, including Lionel Jaffe, who uses a vibrating probe 

 to analyze the role of ionic currents in development and regeneration, for 

 example. 



Within the context of discussion about the relative importance of 

 epigenesis and preformation, and about morphology and physiology, came 

 other debates about the relative roles of cytoplasm and nucleus in heredity 

 and development. A number of European researchers had begvin by 1900 

 to accumulate data from observations made witli improved equipment (oil 

 immersion lenses and effective microtomes, in pailicular) and techniques 

 (stains, fixing agents, preservatives). These studies suggested that there 

 might be sometliing important in tlie nucleus. Indeed, that stainable mate- 

 rial in the nucleus — appropriately labeled as tlie chromatin — might retain 

 its autonomy in the course of cell divisions and might have sometliing to do 

 with heredity. Because the only thing inherited directly and as a whole from 

 one generation to the next is the egg, and because this generation of 



