112 TIMOTHY RICHARDS LEWIS. 



substance slightly different from that of the body ; or may have 

 been retracted during the drying. I have prepared micro- 

 photographs of slides prepared in both ways/ hoping that possibly 

 an image of the entire lash might thus be obtained, even 

 though the eye could not distinguish any, but have not suc- 

 ceeded, notwithstanding that the rays of Kght were caused 

 to pass through glass of various colours. The logwood solu- 

 tion recommended by Koch for this purpose also failed in my 

 hands. 



It is not possible to secure accurate measurements of these 

 organisms during the period of inactivity, nor of the lash at any 

 time, seeing that the latter becomes for the most part invisible 

 in preserved preparations. The body-portion, however, may 

 readily be measured after they have been killed by means of osmic 

 acid. The width of the anterior half, or body-portion, averages 

 •S to Iju, or precisely that of ordinary blood-bacilli, and its 

 length from 20 to 30/i, or an average of 25ju. Ihe flagellum, so 

 much of it as is visible, is somewhat of the same length, so that 

 the total length of the organism equals about 50ju, or about 5^-0". 

 The lash, however, may be considerably longer than this, as the 

 slope from the body-portion is very gradual, and when the eye 

 follows it to the bounds of visibihty an impression is conveyed 

 that there may be still more of it, beyond the power of either 

 Eoss' -Jj" or Powell and Lealand's -^" to reveal. 



They are not very sensitive to the action of reagents ; a weak 

 solution of ammonia did not affect them for some time, but a 

 stronger solution of potash affected such of them as it came into 

 contact with at once : others in the middle of the field continued to 

 exhibit movements for several hours ; probably they had not 

 been touched by the potash. A weak solution of bichloride of 

 mercury in acetate of potash and camphor water (as used for 

 preserving preparations) did not seem to affect them materially, 

 seeing that they maintained their activity in such a solution for 

 eight hours. They retain their vitality longer in a weak salt- 

 solution than in pure distilled water. A cover-glass with an 

 aqueous solution containing them was inverted over a bottle of 

 chloroform for several minutes, but the movements of the 

 organisms were unaffected; if, however, a drop of blood contain- 

 ing them be similarly placed over chloroform they disappear, 

 probably owing to the action of the chloroform-vapour on the 

 blood itself. 



A drop of the blood, was placed on a slide arranged for the 



^ Two such illustrations have been reproduced by the permanent pho- 

 tographic process of the Antotjpe Company, and will be issued with the 

 complete paper iu the Goverument of India Sanitary Report already 

 referred to. 



