142 SUMMARY OF CURRENT RESEARCHES RELATING TO 



obtained which excited as active a fermentation as the fresh yeast from 

 the breweries, a result not always obtained by the use of artificial 

 nutritive solutions. The original gelatin plate-cultures, on account of 

 their rapid growth, were useless after thirty-six hours, and to avoid a 

 constant renewal of the process, as well as tho introduction of different 

 species of Saccharomycetes, inoculations were made into gelatin tubes. 

 The cultures thus obtained produced characteristic, elegant, ivory- 

 white colonies of 3-6 mm. in diameter, and then farther development 

 ceased. In this state they retained their vitality, and were constantly 

 referred to as a source of inoculating material for two months. Probably 

 they remained vigorous much longer, as Saccharomycetes are well known 

 to do, but at this time the author's need of them came to an end. 



Improvement in the method of preparing Blood-serum for use in 

 Bacteriology.* — Dr. A. C. Abbot fills a large vessel, which can be her- 

 metically sealed, with blood taken directly from the neck of an animal, 

 with the usual antiseptic precautions. It is then quickly closed and 

 allowed to stand for 15-20 minutes until coagulation takes place ; a 

 sterilized glass rod is then introduced in order to break up any adhesion 

 of the surface to the glass vessel. The vessel is then placed in a cooler 

 temperature which should not be too low lest coagulation be interrupted. 

 In 24-36 hours the serum is withdrawn with a pipette, and placed in a 

 vessel closed with cotton wool. The latter is then packed in ice for at 

 least three days in order to allow the coloured particles to subside. The 

 clear part of the serum is then transferred in quantities of 60-75 c.cm. to 

 sterilized flasks of 100 c.cm. contents. Discontinuous sterilization is 

 then begun and continued for an hour a day for six consecutive days. 

 For this, the temperature should never be higher than 64° C, nor lower 

 than 58° C. ; for at higher temperatures the serum loses its transparency, 

 and at a lower one the microbes are not destroyed. Thus prepared, 

 serum has been kept for a whole year in the laboratory of the Johns- 

 Hopkins University. 



Improved method for cultivating Micro-organisms on Potatoes.f — 

 Dr. 0. Katz recommends the following procedure for cultivating micro- 

 organisms on potato, which he has found to give satisfactory results, 

 especially in cultivations from dejecta of typhoid patients. 



Test-tubes, 10'5 cm. high and 2-5 cm. in diameter, are plugged 

 with cotton-wool and then sterilized in the usual manner. Potato slices 

 cut out of medium-sized, oval-shaped, perfectly healthy potatoes, and 

 about 1 cm. thick, are placed with forceps in the test-tubes, to the width 

 of which they are made to fit. The tubes are then sterilized again at 

 212° F. 



There is no fear of desiccation of the potato surfaces, as after boiling 

 in the steam sterilizer, there is sufficient fluid at the bottom of the tube 

 to keep the contents moist for a considerable time at a temperature from 

 20°-25° C. (68°-77° F.). At higher temperatures the development of 

 micro-organisms is so much accelerated that there is no danger of desic- 

 cation, but if there should be any fear of its occurrence, the cotton-wool 

 plug may be covered with an indiarubber cap. 



In practice both sides of the potato are inoculated either from the 

 same or from different colonies. 



* Medical News, 1887, i. p. 207. 



t Proc Linn. Soc. N. S. Wales, ii. (1887) pp. 187-90 (2 figs.). 



