APPENDIX A. 



On some Organisms, and other products of uncertain nature, 

 met with in boiled solutions of Ammonic Tar tr ate, and 

 also in others containing Ammonic Silicate. 



MANY observations and experiments have been made with 

 solutions containing neutral ammonic tartrate and neutral 

 sodic phosphate, both in distilled and in tolerably pure undis- 

 tilled water 1 . When these solutions have not been boiled, and 

 have been maintained at a temperature of 65-75 F., they 

 have become more or less turbid in from forty -eight to 

 seventy-two hours, owing to the development and multipli- 

 cation of myriads of Bacteria and Vibriones. If they were 

 previously boiled, however, they were not at all prone to 

 become turbid, and might then be kept for a long time, even 

 with free exposure to the atmosphere 2 , without any trace of 

 the presence of such organisms; though at any period the 

 solutions may be shown to be eminently favourable media for 

 the development and multiplication of these organisms, since, 

 after they have been purposely brought into contact with a 

 few of them, the solutions speedily become turbid and swarm 

 with Bacteria and Vibriones. An utter absence of living 

 things of this kind has, however, always been a notable 



1 In the proportion of ten grains of the former and three grains of the 

 latter to one fluid ounce of water. 



2 This freedom from turbidity may be seen, either in open flasks, in 

 flasks closed with or without ordinary air, or in other sealed flasks to 

 which only air which has been filtered through cotton-wool is admitted. 



VOL. ii. a 



