316 Transactions. 



of tlie saline in which the tutin was dissolved ; and a fourth drop, to which 

 a drop of a 0-1-per-cent. solution of quinine-sulphate had been added, was 

 used for the sake of comparison (Exp. 118). In fifteen minutes no para- 

 moecia were found moving in the quinine preparation, but monads were 

 still in motion. In the three other specimens no change was observed. 

 In thirty minutes all movement had ceased in the quinine preparation. 

 In the tutin preparation paramoecia could still be seen moving, but their 

 movements seemed to be somewhat irregular ; amoebae, bacteria, and monads 

 were still moving. In one hour one or two paramoecia could still be seen 

 moving in the tutin preparation ; they were by no means so numerous as 

 at first, and rather difficult to find. Many of the monads were as active as 

 ever, and amoebae were still throwing out pseudopods ; but the preparation 

 did not present the same appearance of general activity that it did at first. 

 The saline preparations and the control were as active at the end of the 

 experiment as they were at the beginning. 



A further experiment (Exp. 119) was made by covering a drop of hay- 

 infusion with a cover-glass, and then placing a drop of 0-1-per-cent. tutin 

 solution on the edge of the cover. It was observed that such paramoecia 

 as swam out into the drop of tutin solution remained in that drop, displayed 

 irregular movement, and in a few minutes came to a standstill, and appeared 

 to undergo internal disintegration, whicli reduced them to unrecognisable 

 masses. The experiment was repeated with a drop of a 0-5-per-cent. solu- 

 tion tutin in distilled water, with similar results (Exp. 120). 



It would appear, therefore, that paramoecia are injuriously affected by 

 the poison, but not in so great a degree as they are by quinine. On amoebae, 

 dilute solutions (about 0-05 per cent.) have very little influence. Monads 

 are affected in a lesser degree than paramoecia. 



10. Action on Bacteria. 



(Exp. 121.) This was tested by placing pieces of fresh mince in test- 

 tubes containing solutions of tutin of different strength (0-1 to 0-5 per cent.) 

 and a piece in a test-tube containing normal saline alone. The tubes were 

 left open to the air for twenty-four hours, and then corked and placed in 

 an incubator at 37° C. Two days later the tubes were examined, and it 

 was found that the tube containing saline was very offensive, but the tubes 

 containing tutin solution were not at all offensive, and smelt rather like 

 stomach-contents. 



When subjected to microscopic examination, it was found that all the 

 solutions contained bacteria, but in the slide prepared from the normal 

 saline the bacteria were very much more numerous, and showed a greater 

 variety of form and size. It Avould appear, therefore, that tutin has a 

 deleterious action on certain forms of bacteria, but not on all. 



That some forms of bacteria are certainly not affected by tutin is shown 

 by the following observation : A 0-5-per-cent. solution of tutin in normal 

 saline which had been allowed to stand for six months in the laboratory 

 was examined microscopically, and found to contain fairly numerous large 

 motile bacilli resembling B. suhtilis. A green growth that had developed 

 and formed a layer at the bottom of the bottle was found to consist of small 

 rounded yeast-like cells tinged with chlorophyl. 



11. Action on Yeast. 



The action of tutin on the fermentation of glucose by yeast was studied 

 in a few experiments (Exps. 122, 123, 124). It was found that fermentation 



