1894.] MICROSCOPICAL JOURNAL. 281 



some; but, if the demonstrator be provided with an optical \an- 

 tern, and he is able to exhibit the photograph of a chosen sec- 

 tion of the tissue under consideration, he can point out its sal- 

 ient features to all the students at the same moment, and no 

 one can comi)lain that he is not as well off as his neighbor. Mr. 

 Pringle then proceeded to give evidence of the advantages which 

 he claimed for lantern demonstration by exhibiting a large 

 number of photographs on the screen. First he showed some 

 photographic preparations, which were exceptionally fine, 

 among which were a slide of " voluntary muscle" by himself, 

 an example of ossifying cartilage (Klein), a complete section of 

 the human eye, showing very beautifully the cornea, crystal- 

 line lens, the retina, and the optic nerve, and a fine sample by 

 Bousfield of Cortis' organ of the inner ear. 



Next came some very beautifully executed photo- micro- 

 graphs of bacteria, including a "plate culture" of Proteus 

 (Klein) ; two examples, showing bacteria in the dentile tubules 

 of decaying teeth (Sewill), and a splendid example of anthrax 

 bacilli in mesentery, b}'^ Pasteur. 



The consideration of preparations of great rarity came next, 

 and as an example of these were shown that happily rare or- 

 ganism known as Filaria sanguhm hominis, a parasitic, worm- 

 like creature, which, as its name implies, finds its habitat in hu- 

 man blood, but more particularly in the blood of negroes. 

 Three slides referring to this interesting organism came under 

 review by the lecturer, showing — (Ij its ordinary appearance; 

 (2) the sheath of the parasite; and (3) the number of parasites 

 in the restricted field of the microscope ; and the comparative 

 size of F. nocturna (so named because it is only found in the 

 night time) and F. perstans. 



Then came a few words about objects which exhibited unusual 

 difficulties in preparation, and as an example of these the lect- 

 urer exhibited a photograph of Cholera Bacilli, with their fiagelhi 

 plainly visible. These flagella are most difficult to see, even to 

 a trained microscopist, and it might easil}' have been asserted 

 that a man had fancied he had seen them, and that they did not 

 really exist; but here was the photographic record which cleared 

 up the doubt conclusiveh'. Another example of the Bacillus 

 tenno, also showing fiagella, was thrown upon the screen, and 

 the lecturer explained that in this case the hairlike flagella had 



