498 Br. A. Bownes and Mr. T. P. Blunt on [Bee. 6, 



Potassic Carbonate, 0*6. 

 Ammonium Phosphate, 1. 



Solution neutralized with Ammonia and filtered. 

 B. — Approximately the same as last, but the ingredients not weighed. 



Unless otherwise stated, the tubes were always prepared and exposed 

 as in Observation 1. 



It is self-evident that tubes exposed with a south-easterly aspect would 

 receive but a fraction of the total solar rays each day. We have not, 

 however, been able to place them in a position where they would be under 

 the direct influence of the sun during the whole period that it was above 

 the horizon ; with such an arrangement we should expect to obtain results 

 proportionately greater. 



[Received November 5 ; 1877.] 

 Postscript. 



We have stated in the preceding paper that, on exhausting tubes con- 

 taining solution A by means of a Sprengel pump and sealing them, we 

 found that not only, as might be expected, did no development ■ of 

 organisms occur under these conditions, but that if the vacuum was 

 maintained for a sufficient length of time, the solution became absolutely 

 barren. Knowing the necessity of oxygen to Bacteria (of the ordinary 

 kind at least), and taking into consideration the products of their 

 u respiration," we inferred that this result was attributable to the absence 

 of oxygen, and consequent asphyxia not only of the mature forms of 

 those organisms visible to the higher powers of the microscope, but also, 

 t necessarily followed, of that rudimentary " germinal " material which, 

 eluding even the piercing test of the electric beam, is distributed with 

 extraordinary uniformity in almost every water. 



We observed, also, that we have since learned that this mode of 

 sterilization has been recently demonstrated by Professor Tyndall, with 

 a similar interpretation, and on this account we did not consider it 

 worth while to enter upon any details of our own experiments in this 

 direction. Within the last few weeks, however, we have, by employing 

 urine as the experimental fluid, obtained results of considerable interest, 

 and have thought it well to append some account of them. 



Observations with tubes exhausted at the Bprengel pump. 



Obs. 1. July 18. — Two tubes containing Pasteur solution were ex- 

 hausted. The one (a) was at once sealed off ; the other (b) was left 

 attached to the pump (the vacuum being maintained) for three hours, 

 air carefully filtered through cotton wool being then gradually admitted. 

 On July 23 the cor tents of b were found to be turbid. 



On July 26 air was admitted with similar precautions into tube a by 



