166 Transactions of the 



I nest largely diluted some water that had been filtered through 

 animal charcoal, and subjected a portion of the mixture of filtered 

 and unfiltered water to the sugar test, when an abundance of fine 

 filaments was developed. These filaments were not identical with 

 those produced in the presence of urine ; but the difference was 

 probably due to my not having arrived at the proper conditions. 



From what has been stated it will be seen how easily by a slight 

 change of conditions the hne of development of Uving things may 

 be modified, and this is one of the great difficulties to be contended 

 with in attempting to establish whether a water is impure or not, 

 from the development therein of any particular organism ; and it is 

 even possible for a water under certain conditions to contain com- 

 buied nitrogen without producing, when submitted to the sugar test, 

 any turbidity. 



Dr. Frankland, whose researches on this subject are full of 

 interest, was the first to make the observation that effiuent sewage 

 water, when passed through a thick bed of gravel, was deprived of 

 its phosphates, and that although containing combined nitrogen, the 

 water, when submitted to the sugar test, remained bright. 



I was unsuccessful until within the last few days in obtaining any 

 filamental growth from vegetable albumen approaching in appear- 

 ance the filaments that occur in water containing sewage. A small 

 quantity of partially purified vegetable albumen was introduced into 

 New Eiver water contained in an open glass vessel and left for nine 

 days, at the expiration of which time the water contained filaments, 

 both in strings and fi\agments, the latter being almost undistinguish- 

 able from those found in effluent sewage waters. 



While making the experiments with urine and phosphates I 

 also made many with sewage and effluent sewage water under 

 various conditions. There happens to be near me a farm on which 

 the sewage of Epsom is utilized, and I obtained various samples of 

 the sewage as it entered the farm, and of the effluent sewage water, 

 and also samples of the latter after it had become mixed with the 

 water of a brook. 



In dealing with such samples as these in their normal condition, 

 and examining them microscopically from time to time, the first 

 thing that strikes an observer is their capability of producing a great 

 variety of life without the addition of sugar or any extraneous sub- 

 stance, and when, after various degrees of dilution, the samples are 

 submitted to the sugar test, they become less or more turbid, and 

 contain variable proportions of fine filaments and bacterian bodies. 



In effluent sewage water, I have rarely met with the filaments 

 in that beautiful network form in which they are found in water 

 containing only urine or a phosphate ; but there is no difficulty in 

 deciding that both filaments belong to the same class of growth. 



The fflaments met with are of at least two sizes ; one is so fine 



