THE MICRO-ORGANISMS PRESENT IN THE ATMOSPHERE. 
133 
Rate. —34 strokes per minute. 
Control-tube containing plug of sugared glass-wool and sugar-powder.— 
No. 2. Time,— 12.17 to 12.48 p.m. 
Volume of air =30 litres. 
Construction of plug. —Sugared glass-wool and sugar-powder. 
Rate. —3‘3 strokes per minute. 
No control-tube, the above being considered applicable. 
No. 3. Time. —2.42 to 4.20 p.m. 
Volume of air =60 litres. 
Construction of plug. — Sugared glass-wool and sugar-powder. 
Rate, —2*4 strokes per minute. 
Control-tube containing sugared glass-wool and sugar-powder.— 
No. 4. Time. —4.25 to 5 p.m. 
Volume of air = 30 litres. 
Construction of plug.- —Sugared glass-wool and sugar-powder. 
Rate. —3 # 4 strokes per minute. 
No. 4 „ 27 
IV. Laboratory window. October 4, 1886. No. 1 and No. 2 alternated in aspira¬ 
tion. 2.17 p.m. to 3.17 p.m. Wind S.E., very gentle, constant in direction. 
No recent rain. 25 0, 6 C. 
No. 1 . Volume of air = 24 litres. 
Construction of plug. —Sugared glass-wool only. 
