400 ANNUAL REPORT SMITHSONIAN INSTITUTION, 196 2 



tlie almost microscopic fertilized egg ; and that somehow in this small 

 sphere there must be contained the specifications, the directions, or the 

 architectural blueprints for making one of us out of that bit of jelly- 

 like material. Of course, the process by which tliis happens is enor- 

 mously complex, and we do not yet understand very many of the de- 

 tails. But we do know that a substantial part of these directions is 

 wrapped up in the centrally located nucleus of the cell. These direc- 

 tions are the material heredity that we received from our parents. 



In addition to this set of directions in the nucleus, there must be more. 

 There must be an architectural organization of the rest of the cell — 

 the cytoplasm — and this is indispensable. And for the carrying out 

 of the directions there must be a proper supply of raw materials in the 

 form of food — perhaps 10 or 20 tons — for the egg to grow and differ- 

 entiate into a mature person. Time, too, is essential — 16, 20, 25 years, 

 or more. Finally, there must be a proper enviromnent, initially a 

 very precise one. Later, as we develop the ability to regulate our own 

 environments, we become less fussy. The environment adds to the 

 information in the original egg. This is particularly impressive in 

 our own species, for in addition to all the other environmental infor- 

 mation fed into us during development we are continually bombarded 

 with a cultural inheritance — language, art, music, religion, history, sci- 

 ence, and so on — that in man supplements biological inheritance to 

 a far greater degree than in any other species. 



All these factors are essential to our development, and many of 

 them continue throughout life. In these halls I do not need to em- 

 phasize the significance of cultural inheritance, for it is a primary 

 function of M.I.T. to add to that cultural inheritance and to teach us 

 how more effectively to pass it on in a manner that will be cumulative 

 from generation to generation. 



What I wish to talk about are the directions in the nucleus. "Wliat 

 are they and how do they specify that from this minute cell one of 

 us will come ? I shall ask five questions about these specifications : 



First, how do we get them and how do we transmit them ? I shall 

 dispose of this one briefly, for it is answered by classical genetics — 

 the Mendelian genetics now found in every elementary textbook of 

 modern biology. You know about classical genetics : about blue eyes, 

 brown eyes; curly hair, straight hair; good hemoglobin, bad hemo- 

 globin ; and so on. 



Perhaps you know less about the remaining four questions: 



How are the specifications written — that is, what is the language of 

 genetics ? 



How are the specifications replicated ? From the time we start de- 

 velopment as a fertilized egg until we transmit them to the next gen- 

 eration there are perhaps 16 to 25 successive replications of these 

 specifications, depending on whether the carrier is female or male. 



