80 FRANCIS DARWIN. 



CarLolicAcld. — Pure crystallised acid sold as "absolute phenol'' 

 was em])loyed, and a 2 per cent, solution made with distiiled 

 water. This proved fatal at ouce, causing contraction of the fila- 

 ments. The same effect was caused by 1 per cent, solution, and 

 specimens mounted in 1 per cent, produced no filaments. On 

 the other hand, ^ per cent, is certainly innocuous. Thus, in one 

 of several experiments a preparation mounted at 3.5 p.m. in 

 water was thoroughly irrigated with \ per cent, carbolic acid ; 

 at 3.35 there were many extended filaments. The preparation 

 was then irrigated with -'„ per cent, thymol solution, and the 

 filaments contracted in three minutes. These results agree with 

 the above statement that thymol is far more poisonous to low 

 organisms than is carbolic acid. Moreover, the fact that \ per 

 cent, is not poisonous to the filaments is what might be expected 

 on the assumption that they are protoplasmic. For Dr. Baxter 

 has shown^ that contagia, microzymes, &c., are not destroyed by 

 1 per cent, solution of carbolic acid. Thus with vaccine less 

 than 1 per cent, has no effect, 'Z per cent, is fatal ; infective in- 

 flammation, less than 1 per cent, no effect, 1 or more per cent, 

 fatal. Virus of charbon, less than 1 percent, no effect (Devaine). 

 Dr. Baxter also proves the same thing for the virus of glanders 

 and for microzymes in Cohn's fluid. It should be added, however, 

 that the spores of PenicUlium are killed by -pL, per cent. 



The results of the experiments with sugar solutions are per- 

 haps worth noting. I was surprised to find that filaments were 

 protruded in 12 per cent, solution of sugar. I therefore mounted 

 other sections in water, and irrigated (5.30 p.m.) with 20 per 

 cent, of sugar solution. At 5.4-0 I saw well-extended filaments 

 on three glands, and there was no shrinking of the gland-cells. 

 I then added more sugar to the solution, so as to make it up 

 roughly to 30 per cent. At 6.14< irrigated with 30 per cent, of 

 sugar. At G.i7 the gland-cells slightly shrunk, but filament not 

 contracted. At G.21 all the four glands under observation have 

 their 6'^/^* shrunk ; one filament quite, another nearly contracted, 

 and two still extended. At 6,47 irrigated with 35 per cent, 

 (roughly). At 7.2 irrigated with 4<0 ])er. cent, (roughly). At 

 7.0 two filaments still uncontracted. At 7.14 preparation irri- 

 gated with si/rup of sugar, and contraction took place in a few 

 minutes. 



The following experiment was made with sugar solution of 

 between 44 and 45 per cent. A preparation was mounted in water 

 at 3.43 p.m., and irrigated with the sugar solution. At 3.56 

 the filament under observation contracted, and at 4 no extended 

 filaments were to be found in the preparation. A solution of 45 



' * Report of tlic McdicMl OITicer of the Privy Ceuucil,' new series, vi, 

 1875, pp. 225, 237, 215, 219, &c. 



