ON THE DIFFERENTIAL REACTION TO VITAL DYES EXHIBITED 

 BY THE TWO GREAT GROUPS OF CONNECTIVE-TISSUE CELLS. 1 



INTRODUCTION. 



Within the last decade a prodigious mass of accumulated observations on the 

 blood and connective-tissue cells has undergone systematic critical revision. 

 Clear-cut anatomical data have been secured. If it must be confessed that we have 

 not yet solved fundamental problems in the origin and cause of differentiation of 

 these various elements, we are at least informed as to the number and kind of such 

 elements. Histological, pathological, and clinical observations have gained assort- 

 ment and appraisal. In the possession of the histological studies of Maximow, 

 the investigations of modern cellular pathologists, among whom we may name 

 Marchand and Aschoff, and the hematological critiques of Turk, Naegeli, Pappen- 

 heim, and Weidenreich, we are justified in feeling that all of the ordinary his- 

 tological facts have been clearly established. Further inquiries can be undertaken 

 and will have significance by virtue of this preliminary information. 



Perhaps no inquiries have received attention commensurate with that accorded 

 the interrelations of the cells of the blood and supporting tissues; for, though both 

 these cell groups have been accurately explored, we know as yet but little of their 

 affinities, the one to the other, or of their exchanges, if such occur. The doctrine 

 of a strict separation of these two broad cell categories has been sharply attacked. 

 The connective tissue is the ancestral and the ontogenetic home of the blood, says 

 Weidenreich, nor does it ever wholly lose its considerable blood-cell content in 

 normal life. It is perhaps because of these intimate relations with the blood-stream 

 that, to most histologists, the connective tissues present a more complex cellular 

 picture than they actually possess; but, besides the blood, the development of 

 certain of its cells for the storage of fat, and, again, the presence of histiogenous 

 mast-cells, have also added complexity to the subject. 



In the descriptions furnished by every modern investigation, although the 

 fact has not yet "settled out" into text literature, the connective tissue is an 

 exceedingly simple and constant substance, for but two great groups of cellular 

 inhabitants occur in it. Originality can hardly be claimed for this statement, 

 yet it deserves reiteration. Attention to the demonstration of lymphocytic emi- 

 grations from the blood-stream into the connective tissue and to the ensuing 

 " polyblastic " transformation of these cells, or, again, the belief that " rhagiocrine " 

 characters are originally universal in connective-tissue cells and may at any time 



1 The present communication constitutes the fifth of a series devoted to the phenomena of vital staining with the acid 

 dyes by Herbert M. Evans and Werner Schulemann. Most of our vital dyes wte secured in the course of this previous 

 joint work of Evans and Schulemann. The world conflict and its crucial alinements of loyalty have taken an inevitable toll 

 in that plan. But neither this nor any other possible calamity could absolve a deeply felt obligation to acknowledge the 

 credit due this previously loyal and generous collaborator, with whom contact has been impossible for a period of over 

 six years. 



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