2 CHARLES F. W. McCLURE 



10. On the reactions of the tissues toward colloidal acid dyes during the sea- 



son of hibernation 40 



11. On the causes which underlie the initiation of the process by which dye 



granules are stored in the cytoplasm of certain typical cells of the 

 embryo 43 



12. Does the method of vital staining by colloidal acid dyes contribute any 



evidence in favor of the view that the lymphatics are derived from the 

 veins? 50 



13. The progressive reactions of the tissues toward colloidal acid dyes as 



observed in the course of larval development 54 



14. Summary 60 



Literature cited 62 



1. INTRODUCTION 



A study of the reactions of living tissues toward colloidal acid 

 dyes has within recent years claimed the attention of a good 

 many investigators. Investigations have thus far of necessity, 

 however, been confined, for the most part, to a study of tissues 

 in adult animals. Evans and Schulemann ('14) have advanced a 

 strong argument in favor of the view that vital staining of certain 

 tissues by colloidal acid dyes is purely a physical process and 

 primarily one of ingestion or phagocytosis. This process consists 

 in the ingestion by the cell of ultramicroscopic colloidal particles 

 of dye which become stored in its cytoplasm in the visible form 

 of what are now commonly designated as dye granules. 



Although there appears to be little if any doubt that colloidal 

 dye particles are taken up by certain types of cells by a process 

 of phagocytosis, there may still be some doubt whether all of the 

 cells which have thus far been observed to react toward these 

 dyes may do so in exactly this same manner. While fully appre- 

 ciating that the method by which dye gains entrance to the cell 

 and that the significance of the reactions observed may not be 

 the same in all cases, the nature of this investigation which deals 

 chiefly with the portal of entry of the dye and its transportation, 

 has demanded, in considering their behavior, that all tissues which 

 react toward the dye should be considered more or less in common 

 (Chapter 11). 



A comparison of the tissues which react toward colloidal acid 

 dyes, as thus far observed in vertebrates, shows that they are for 



