8 CARNEGIE INSTITUTION OF WASHINGTON. 



in its earliest stages. There has been increasing evidence of need for 

 study of the physiological reactions in all embryonic material avail- 

 able for investigation coupled with adequate morphological control. A 

 program of research has now been outlined which will make it pos- 

 sible to take immediate advantage of every opportunity for these 

 exceedingly important and critical studies. 



In the special researches conducted independently by the Depart- 

 ment of Embryology, significant advances have been made in 

 many directions, ranging from a study of fundamental problems con- 

 cerning growth of tissues in the body to the value of racial 

 characteristics in early embryonic stages. The work of W. H. Lewis in 

 this Department gives us this year for the first time a demonstration 

 of the manner in which one of the primitive embryonic tissues in the 

 body known as "indifferent mesenchyme" becomes converted into 

 such highly specialized membranes as those lining the thoracic and 

 abdominal cavities. 



Through studies carried on in many laboratories in recent years, a 



great body of knowledge has been accumulated which bears upon the 



Genetics mechanism of heredity. While very much remains 



and Ecology. ^q \^q known in this field, classic researches like those 

 of T. H. Morgan, a distinguished associate of the Institution, have 

 gone far to give us an understanding of the process by which the char- 

 acteristics of individuals are carried over or combined in succeeding 

 generations. 



In our Department of Genetics significant advances have been made 

 in studies conducted by A. F. Blakeslee and John Belling on variation 

 in the elements of the cell recognized as bearers of characters transmit- 

 ted to descendants. In addition to investigation of the mechanism 

 of the cell in its relation to heredity, progress has been made on the 

 experimental side in the induction of mutations or variations in cer- 

 tain plants and in the interpretation of factors which seem to have 

 produced such variation of the cell structure. 



One of the great opportunities for future research in biology seems to 

 lie in the consideration of influences which alter the course of life suc- 

 cession. There is strong suggestion that determination of the char- 

 acteristics of a given generation may not depend solely upon elements 

 contributed directly by the ancestor or ancestors. Influences external 

 to the original elements of the cell, exerted perhaps by purely physical 

 or chemical processes, may be responsible for some of the deviations 

 from original type. 



The difference between a situation in which the qualities of a new 

 individual depend entirely upon original characteristics of the ances- 

 tors, and one in which the individual peculiarities are even in small 



