TRANSACTIONS OF WAGNER 

 52 



MENDEL AND HIS LAW 



singularly uneventful, when looked at from this standpoint. Like many other 

 scientists, his approach was through the study of medicine. He got his training 

 and his medical degree at Gottingen. After practising medicine for a little 

 while he went for further study to Vienna for a year, for another year to Italy, 

 and finally to Paris. Then comes a short interval of medical practice, but his 

 scholarly tastes drive him once more to the laboratory and he goes to Giessen 

 to study under Leuckart. Now instead of returning to the practice of medi- 

 cine, he goes to the University of Freiburg, in 1866. Beginning there at the 

 bottom in the department of zoology, he passes through all the grades of teach- 

 ing until he reaches the honor of the full professorship. This chair of zoology 

 he held up to the time of his death in 1914. His preceptor, Leuckart, had been 

 a famous student of parasitism, and it was perhaps this which led Weismann to 

 the study of certain members of the fly family which are parasitic on or in 

 animals or are in other ways troublesome to man. This led to the study of 

 the life history of these insects, which involved careful and very accurate work 

 under the microscope. 



In order that those unaccustomed to the nature of this instrument should 

 have some idea of what is meant by microscopic work it may not be amiss to 

 describe some of the refinements of practice which have developed within 

 Weismann's working years and in the use of which he was most assiduous. 

 Work with the microscope does not mean simply looking at things under the 

 microscope. Some of the most diflicult parts of the work must be done before 

 the object can be placed under the glass for examination. The preparation of 

 objects for the microscope has more refinements than the observation of the 

 material after it is once prepared. In the earlier days of biologic study, not 

 over fifty years ago, it was considered quite sufficient for most purposes that 

 the animal should have been killed by any method which brought about its 

 death in decent and seemly fashion. An animal killed by chloroform and then 

 preserved in alcohol was considered perfectly good material for microscopic 

 work. Such a preparation served entirely for all ordinary dissection. When 

 it came to the study, not of the number and size of the cells, but of their inter- 

 nal structure, it became gradually more and more clear that the cells of animals 

 killed in such fashion do not bear in death even a remote resemblance in inter- 

 nal structure to that which had been theirs in Hfe. It was clear that there 

 were very profound changes within the cell on and after death. It became 

 essential, then, that tissues must be brought quickly from life to death and not 



