Subject d) Nucleo-cytoplasmic relations 

 chairman: Prof. J. Brachet (Brussels) 

 main speaker: Dr W. S. Vincent (Syracuse, N.Y.) 



Sub-topic B: PROGRESSIVE MATURATION OF THE ORGANIZAT- 

 ION PATTERN IN FERTILIZED AND CLEAVING EGGS 



Subject e) in Spiralia 



chairman: Prof. F. E. Lehmann (Bern) 

 main speaker: Dr. R. Weber (Bern) 



Subject f) in Ascidians 



chairman: Prof. G. Reverberi (Palermo) 

 main speaker: Dr. A. Minganti (Palermo) 



Evening lecture on "Ultrastructure of sperm and its changes during fertili- 

 zation" by Dr. A. L. Col win (New York) 



The subjects d, e and f and the second eveninq lecture will be held on Friday, 

 Sept. 16. y 



Subject g) in Arthropodes 



chairman: 



main speaker: Prof. G. Krause (Wurzburg) 



Subject h) in Echinoderms 



chairman: Prof. J. A. M. Runnstrom (Stockholm) 

 main speaker: Dr. A. Lallier (Paris) 



Subject i) Development of symmetry in Vertebrates 

 chairman: Prof. Et. Wolff (Paris') 

 main speaker: Dr. J. Clavert (Strasbourg) 



Demonstration of films in the evening. 



The subjects g, h and i and the presentation of films will be held on Satur- 

 day, Sept. 17. 



Free papers on subjects which fall within the scope of this Symposium will 

 be given on Sunday morning, Sept. 18. 



Subject j) Role of the nucleus 



chairman: Prof. E. Hadorn (Zurich) 



main speaker: Dr. R. W. Briggs (Bloomington, Ind.) 



Subject k) Topegenesis and topochemistry 

 chairman: Prof. A. Monroy (Palermo) 

 main speaker: Prof. E. Urbani (Camerino) 



Subject I) Early development of special proteins 

 chairman: Dr. J. D. Ebert (Baltimore, Md.) 

 main speaker: Dr. G. W. Nace (Ann Arbor, Mich.) 



The subjects j, k and 1 will be discussed on Monday, Sept. 19. 

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