42 



water taken from 



Mercury 

 Valve 



Alh'Pyroaallo 



FIG. 7. Apparatus for testing the anaerobism of 

 Chara and Nitella (two-thirds natural size). 



PHYSICS OF STREAMING 



the culture-vessel. The tube was placed in a bottle 

 containing a solution of pyrogallol 

 and caustic potash (Fig. 7), which 

 is kept immersed under water. Pure 

 hydrogen (Fig. 6) is then passed 

 through as shown, until the air is al^ 

 displaced. The entry-tube is then 

 clamped and the vessel exhausted by 

 a Sprengel pump. Hydrogen is again 

 passed in, and after one or two repe- 

 titions, the exit- and entry-tubes are 

 drawn out and sealed. The whole is 

 then covered with black cloth and 

 placed in a dark cupboard. The only 

 possibility of error here is that the 

 water might have absorbed oxygen 

 during cooling, but it could only retain 

 the merest fraction of this. More- 

 over, the water in the tubes was 



frequently tested by means of reduced indigo solution immediately on 

 opening, and always with negative result, even if opened the day after 

 sealing. 



Experiments conducted in this manner succeed with sufficient fre- 

 quency to prove conclusively that healthy plants of Chara foetida, Nitella 

 translucenS) N.flexilis, and to a less extent Nitella syncarpa. Char a gracilis> 

 C.flexilis, and C. stelligera may continue at temperatures of from 15 C. to 

 1 8 C. to show slow streaming for from one to several weeks in the entire 

 absence of oxygen. In a few cases small new side sprouts were formed 

 during the first two or three weeks, but not after this. Many filaments of 

 the first three plants were still living after six weeks, and exhibited slow 

 creeping streaming immediately on examination, but in no case did any 

 remain living for longer than eight weeks. The ultimate death is not due 

 to the absence of oxygen, but to mal-nutrition, for darkened parts of Chara 

 and Nitella^ even if attached to the parent plant, die within two months, 

 although supplied with free oxygen *. 



The cells might remain living longer were they provided with appro- 

 priate food and the medium kept sterile, but if they are placed in nutrient 

 solutions containing sugar, glycerine, or asparagin, anaerobic bacteria 

 develop whose by-products rapidly injure the filaments. The oosperms 

 can be sterilized and sown in sterile media, but unfortunately they refuse to 



1 See Ewart, Journ. Linn. Soc., 1896, Vol. xxxi, p. 564; cf. also Ritter, Flora, 1899, LXXXVII, 

 P- 329- 



