Mr Potts, A Note on Vital Staining 231 



A Note on Vital Staining. By F. A. Potts, M.A., Trinity Hall. 

 [Read 22 November, 1920.] 



Great confusion exists as to the phenomena which are classed 

 under the term 'vital staining' but it is established that certain 

 stains can penetrate the living cell and enter into combination with 

 bodies in the cell without apparently affecting the normal course 

 of cell life. These bodies are principally granules of various kinds 

 and some of them are undoubtedly concerned with the process of 

 secretion. How far they are actually part of the living protoplasm 

 is a point at issue. Very little work has been done, in the Metazoa 

 at least, on the further history of stained granules of this kind, 

 and it seems to offer a promising field for students of vital pro- 

 cesses. Exceedingly interesting in this connection are the observa- 

 tions of Oxner* on Nemertines, the mucus cells of which contain 

 numerous granules staining with neutral red and methylene blue 

 but produce colourless mucus. The earlier work of Apathy"}" had 

 brought to light similar effects and is more satisfactory in that the 

 author states that he has seen in the mucus cells of Hirudinea 

 granules stained with methylene blue actually forming blue mucus. 

 It is not obvious that Oxner had definitely traced the genesis of 

 his colourless mucus from stained granules. 



The Nematoda are a group which offers wonderful facilities for 

 researches of this kind, for the smaller members of the phylum are 

 of an almost perfect transparency, are exceedingly hardy under 

 experimental conditions, and contain many kinds of granules which 

 take up vital stains. Cobb % has already indicated this extraordi- 

 nary suitability of the free-living forms in particular and appealed 

 to scientific workers to give their attention to these and other 

 related problems. I wish in this paper to briefly summarise some 

 observations made on a species of Diplogaster which was found in 

 garden soil in Cambridge during 1919. 



Neutral red was found to be by far the most effective stain. In 

 fact no others of those used showed up the granules which I go on 

 to describe here. The solutions employed were very concentrated 

 especially if compared with the exceedingly dilute ones which give 

 the best result for freshwater Crustacea (Fischel) and marine 

 organisms. A solution made up more than ten years ago of neutral 

 red in distilled water was especially good, its staining properties 

 had evidently improved with age and it was almost non-toxic, 



* Oxner, Bull, de Vlnstitut. Oceanograph, Monaco, 1908. 



t Apathy, Zeitschr. wiss. Mikr., Bd. 9, 1892. Cf. also Hardy, Journ. Physiol.,. 

 vol. xm, 1892. 



I Cobb, Natural Science, vol. 46, 1917, p. 167. 



