INTRA VITAM COLOR REACTIONS IN NEMAS 121 



Observing certain precautions, I find that a great variety of coal-tar 

 compounds and other colored compounds can be fed to nemas, ap- 

 parently without interfering materially with their normal metabolism. 

 Some nemas are resistant to chemicals that to most organisms are 

 poisonous. Often I have had the best results by cumulative action, 

 using small quantities of color dissolved in the medium in which the 

 nema lived, and allowing the dye to act for days or weeks. 



Not infrequently the dyes prove to be highly specific in their action. 

 Only certain cells, or only definite parts of certain cells, exhibit visible 

 reactions in the form of colorations. The results obtained by the 

 use of any given dye may be quite varied. It is evident in many cases 

 that the dye is digested and assimilated, thereby undergoing molec- 

 ular changes by which it is converted into new compounds in a man- 

 ner analogous to the processes exemplified in chemical laboratories 

 devoted to the production of aniline dyes. Thus, a dye may give 

 rise to several different colors, none of them like that of the dye itself, 

 and all of them very likely due to new compounds. I have seen con- 

 siderable evidence pointing to the conclusion that in some cases the 

 dye fed is converted into colorless compounds during the process of 

 digestion (a reduction phenomenon?), and these colorless compounds 

 re-converted into colored substances after they arrive at certain des- 

 tinations or conditions. The number of changes these "living lab- 

 oratories" can ring on the molecular structure of a given dye must in 

 some cases be very considerable. Two or more dyes fed simultane- 

 ously sometimes produce results more or less independent of each 

 other. The spectacles are very brilliant. 



Using these methods I have been able to demonstrate within the 

 confines of a single cell the existence of an unsuspected number of 

 kinds of "granules," manifestly playing different rdles. After the 

 differences among these bodies have been shown in this way, it is 

 sometimes possible to perceive corresponding morphological differ- 

 ences; but without the aid of the color reactions the differences "Would 

 never have been suspected. 



The main thing to bear in mind is that on the basis of our present 

 more complete knowledge of the chemical and physical properties of 

 coal-tar compounds these color reactions in living nemas may be made 

 the index of physiological characters possessed by the cells and their 

 components. In view of the great variety of the known coal-tar 

 derivatives, and the wonderfully varied metabolism of the free-living 

 nemas, it seems to me a very reasonable hope that researches directed 



