PRESENT TENDENCIES OF MORPHOLOGY 275 



of microscopical technique due to Leydig, Ranvier, to Max Schultze, 

 to Flemming, etc. 



And these improvements in their turn have been made possible 

 of attainment by the advances of chemistry and especially of the 

 chemistry of dyes (the anilin dyes in particular). Despite the em- 

 pirical and crude way in which we make use of each new con- 

 quest of the physical and chemical sciences, despite the existence 

 of methods, which are still imperfect, such as those of Golgi, of 

 Cajal, and of Apathy, what morphologist would be blind enough 

 to deny the importance of the new data which we owe to technical 

 processes of which the theory is very often unknown to us? But 

 chemistry has rendered us services not less important in enabling 

 us to penetrate into the finer structure of the chromatin substance 

 and of the albuminoids in general. In this fruitful way, which Robin 

 had already attempted, but which has been opened to us by Schut- 

 zenberger and by Kossel, cytological morphology will certainly 

 find the key to many of the enigmas which arrest it at the present 

 time. And what progress shall we not be able to attain through 

 the chemistry of colloids of which our present chemistry is, in a 

 fashion, only a special case. 



That cytological morphology should be contributed to equally 

 and in large measure by physics and especially by optics, is too 

 evident to be necessary to insist upon. I desire only incidentally 

 to make a remark which will show what influence scientific studies 

 which are very dissimilar in appearance may have upon one an- 

 other. 



There is no doubt that the perfecting of micrographic apparatus, 

 and especially of immersion objectives, has been due in such large 

 measure to the desire of the constructors to satisfy a clientage 

 which is special and sufficiently large in certain countries, namely 

 the collectors of diatomes, that these amateurs, sometimes unjustly 

 disdained by those who wish to establish air-tight partitions between 

 scholars of different orders, have indirectly rendered great service 

 to pure histologists and to those who study the most delicate pro- 

 blems of cytology and of cytogeny. 



The bacteriologists, while aiming at a very different and much 

 more practical goal, have contributed still more than the diatomists 

 to the perfecting of our micrographic equipment in extending to a 

 new class of investigators, the pathologists and clinicians, the daily 

 use of the microscope. 



And in this domain of pathological anatomy we again see pro- 

 duced these very fruitful interactions with the science which more 

 especially interests us. The study of tumors, cellular teratology, 

 at the same time that it is illuminated by the facts of normal cyto- 

 logy, furnishes us with very suggestive views concerning the signi- 



