92 CARNEGIE INSTITUTION OF WASHINGTON. 



We are fortunate in secui-ing the services of Dr. Chester H. Heuser, Associate 

 in Anatomy of the Johns Hopkins University, who joined our staff on July 1, 

 1921. Dr. Heuser received his doctorate under Professor Minot, with whom 

 he acquired a fundamental training in mammalian embryology. He subse- 

 quently continued his studies in embryology at the Wistar Institute, where he 

 remained up to the time of coming to Baltimore. Dr. Heuser has assumed 

 charge of the examination and classification of new accessions. 



As has been our experience in previous years, several visiting investigators 

 have spent longer or shorter periods working with us as space permitted. For 

 the most part they have come either to take advantage of our embryological 

 collection and associated facilities or to acquaint themselves with the more 

 recent work in tissue-culture that is being carried on by W. H. and M. R. 

 Lewis. The profit from these visits is not all one-sided, for such contact with 

 workers from other laboratories is a source of stimulation, suggestion, and 

 criticism and is of great value to our own local group. Professor Bartelmez, 

 of the University of Chicago, has worked with our younger embryological 

 specimens and has practically completed a comprehensive study of the human 

 embryo for the period between 2 and 20 somites. Dr. H. H. Woollard, of the 

 University College, London, has studied the development of the blood- 

 vessels of the arm. His visit here was made possible through the generosity 

 of the Rockefeller Foundation. Professor C. L. Davis, of the University of 

 Maryland, has completed his study of a human embryo of 22 somites. Dr. 



E. D. Congdon, on a year's leave of absence from the Leland Stanford Uni- 

 versity, has traced the history of the aortic arches in the human embryo. 

 Professor H. D. Senior, of the Bellevue Hospital Medical College, New York, 

 has consulted our material in connection with his work upon the develop- 

 ment of the blood-vessels. Dr. Erwin F. Smith, of the U. S. Department of 

 Agriculture, and his associate. Dr. Brown, have studied the methods of 

 tissue-culture with the view to their application to investigations in plant 

 pathology. Dr. J. C. Baldwin, of the Department of Pediatrics, Johns 

 Hopkins Hospital, has studied abnormahties in the growth of the fetus. Dr. 

 W. F. Reinhoff, of the Department of Surgery, has conducted some experi- 

 ments in the growth of kidney tissue with the tissue-culture technique. Dr. 



F, P. Johnson, of the Department of Urology, has modeled the fetal female 

 urethra. Dr. M. B. Wesson, of San Francisco, formerly of the Department of 

 Urology, has continued his embryological studies of the male perineum. Dr. 

 H. S. WiUis, of the Department of Medicine, has cooperated in a study of the 

 effect of avian tubercle bacilli upon tissue-culture growths. Dr. C. C. McCoy, 

 of the Department of Pathology, has determined the power of survival of cells 

 after the death of the animal. Dr. D. T. Smith, who enters the Department 

 of Pediatrics this fall, has continued his studies on pigment-cells. Miss E. B. 

 Finley has studied the histogenesis of blood-vessels. D. M. Rioch, J. L. 

 Wilson, M. Thompson, J. T. Bauer, and K. S. Oliver, all students in the Johns 

 Hopkins Medical School, have worked with Professor and Mrs. Lewis in con- 

 nection with their investigations on tissue-culture. Most of these studies 

 have resulted in papers that are now either in preparation or in the hands of 

 the publisher; they will be described more completely at some subsequent 

 time. A few have been mentioned in the main body of the present report. 



