1882.] 



The Minute Anatomy of the Thymus. 



349 



The influence of roughness in hindering the spread of liquid over 

 the surface of the impinging sphere is then pointed out. 



At the close of the paper an explanation is put forward of the radial 

 ribs, arms, and strias which are a notable feature of all splashes. 

 Measurements of the annular rim bordering a thin central film, into 

 which a drop falling upon a plate passes,* show that the number of the 

 lobes and arms which are subsequently observed, agrees well with the 

 number of drops into which such an annulus would theoretically tend 

 to split if unhindered by friction with the plate on which it rests, 

 and it is then pointed out that the effect of the connecting film 

 would be exactly such as to counteract the influence of this friction. 



In the same way the radial striae and ribs which characterise the 

 hollow formed round a drop or solid sphere impinging on a liquid 

 surface, are accounted for by the instability of the annular rim of the 

 hollow, which through its tendency to cleave into a definite number of 

 drops, determines a corresponding number of lines of easiest flow, at 

 each of which a rib or arm is developed. 



The author has observed that after the details have been once 

 revealed by the method of instantaneous illumination, it is not difficult 

 to identify the broad features of any splash that may occur by 

 attentive observation in continuous light. Such observation may 

 afford valuable information as to the condition of the surface of an 

 impinging solid. 



II. " The Minute Anatomy of the Thymus.'' By Herbert 

 Watney, M.A., M.D. Cantab. Communicated by E. A. 

 S Chafer, F.R.S. Received January 30, 1882. 



(Abstract.) 



Three short notes relating some of the facts mentioned in this 

 research have been published in the "Proceedings," vol. 27, p. 369; 

 vol. 31, p. 326, and vol. 33, p. 11. 



The paper begins with a history of the views which have been 

 held as to the anatomy, physiology, and development of the thymus. 



The microscopical sections in many instances were double-stained 

 by haematoxylin, by using first a red and then a blue solution ; the 

 colours of the solutions depend on the alum used with the haematoxylin 

 extract. The red solutions stain the protoplasm of the cells, the 

 connective-tissue, and the granular cells ; the blue, the lymphoid 

 corpuscles and the reticulum. 



In all mammals the thymus disappears at some period of adult life ; 



* " Proc. Roy. Soc," vol. 25, p. 500, fig. 4. 



