EMBRYOLOGY AND MEDICAL PROGRESS 9 



means of giving us perfectly clear plastic conceptions of the arrange- 

 ment of parts. The very ingenious wax-plate method was invented by 

 the late Gustav Born, who conceived the happy idea of making wax 

 models of single sections or parts of sections equally magnified in all 

 three dimensions. It is only necessary to pile such wax plates in order, 

 one on top of another, to get a correct model of the whole object. 

 The method is very widely used and in my laboratory, for example, 

 has been employed recently by Dr. John L. Bremer to model the 

 anatomy of a human embryo and by Dr. John Warren to model the 

 developing brain. Such models are truly revelations to one who has 

 studied sections only. 



This is not a suitable occasion to review the history of the tech- 

 nical progress of embryological science. I wish only to so far indicate 

 it as may suffice to direct your attention to the dominant importance 

 of method in scientific problems. It seems to me that the greater 

 part of the advance which is made from time to time in modern 

 science is the direct result of either an improvement of old methods 

 or the invention of novel methods. I can see in my own science clearly 

 that this has been the case, and from what I learn about other sciences, 

 infer that it is equally true of them. Viewed from the psychological 

 standpoint, the vast majority of methods have a common purpose, 

 nameh', to present the results to the eye, so that we can see what the 

 facts are with which we wish to become acquainted. When we make 

 sections, it is in order to see the cells in their natural relative posi- 

 tions, and with all their various characteristics. When we stain sec- 

 tions, it is in order to make things visible which were before indis- 

 tinct or perhaps invisible. When we make reconstruction or models 

 it is to furnish again an image to the eye which we can not get from 

 the actual object itself. The eye, indeed, is the chief agent in col- 

 lecting information for us from the objects by which we are sur- 

 rounded. It is because they help out the eye that the microscope and 

 telescope have counted for so much. The eye is almost the monarch 

 of research, and reigns even more supremely over our relations with 

 our surroundings than does the ear over our intercourse with our 

 fellow men. 



The results of embryology for a long time remained rather meager, 

 and when as a young man I went to pursue some of my scientific 

 studies in Germany, the principal text-book of the science was a 

 modest octavo volume by Professor Kolliker. Since that time (1873) 

 the activity in this domain has increased by leaps, and is now enormous, 

 and the latest handbook of the science, that which is in course of 

 publication at this time under the editorship of Professor Hertwig 

 of Berlin, will comprise eight volumes, each of which promises to 

 exceed a thousand pages when complete; yet the work is only a digest 

 of the researches upon the development of vertebrates and does not 



