441 



NOTES ON EXHIBITS. 



By E. M. Nelson, F.R.M.S. 



{Bead Januanj 28/yZ, 1912.) 



Plate 22, figs. 1 and 2. 



The followiug photomicrographs were shown by the Hon. Secretary 

 in the absence of Mr. E. M. Nelson : 



Slide 1. Eye-spot of Coscinodisois aster ortiphalus^ Maryland 

 deposit, styrax mount, showing fracture passing through cap 

 X 3,000 diams. (PI. 22, fig. 1). 



The negative from which this lantern slide was made, by con- 

 tact printing, was taken direct, and neither it nor the lant^ern 

 slide has been intensified, reprinted, enlarged or touched up in 

 any way. (Tliis remark applies to all the slides.) It is obvious 

 that the presence of a fracture proves the existence of a membrane 

 covering the eye-spot (PI. 22, fig. 2). 



Slide 2. Tubercle Bacillus from sputum showing the so-called 

 flagellum x 4,150 diams. 



This preparation was made in the middle of last month 

 (December 1911) by Dr. A. C. Coles, of Bournemouth, who 

 has kindly sent me the following particulars concerning it : 

 " From sputum stained in ordinary way with Ziehl Neelsen's 

 method and decolourised in 25 per cent, sulphuric acid, counter- 

 stained with aqueous solution of methylene blue, and mounted in 

 parolein." 



A curved flagellum has been selected for reproduction in order 

 to meet Dr. Eyre's criticism that the so-called flagellum was a 

 smear from a slipped cover-glass. This flagellum, appendage, or 

 whatever it may be called, of the Tubercle Bacillus was discovered 

 by me in the spring of 1905 when examining a clinical mount for 

 a medical practitioner. The stain in that preparation has faded 

 away, but in other preparations the appendage has been seen by 

 many microscopists, both trained and untrained, to whom others, 

 as well as I, have shown it. 



Slide 3. The above are the first photomicrographs I have 

 made since January 1902, but while my camera was set up the 

 opportunity was taken of photographing a fascinating bit of 

 broken secondary structure to test the photographic qualities of a 

 Leitz apochromat yV of 1*4 N.A. 



