IOWA ACADEMY OF SCIENCES. 145 



shows itself by forming a bubble in the medium surround- 

 ing the colony. As all colonies are below the surface, the 

 number of gas bacteria present in the amount of milk 

 taken will be represented by the number of bubbles appear- 

 ing. If it is desired to make sub-cultures of the gas 

 bacteria it may be done in the usual manner, with the 

 advantage of being able to secure the right one at once. 



One chance for error has been noted. This comes from 

 having too many colonies crowded on the Petri dish, when 

 some of the gas germs will not develop sufficiently to show 

 a bubble. The trouble may be avoided by sufficient dilu- 

 tion. While no exact limit can be set, it seems advisable 

 to have not more than 300 to 500 colonies on a Petri dish. 



Although the writer has made no trials, it would appear 

 that this method might be useful in isolating and counting 

 gas producing bacteria in the examination of water sus- 

 pected of sewerage contamination. 



THE TOTAL SOLAR ECLIPSE OF MAY 2S, 1900. 



OBSERVED AT WADESBORO, N. C. 



BY DAVID E. HADDEN. 



A total eclipse of the sun is always one of the grandest 

 and most awe-inspiring of all natural phenomena. To the 

 superstitious and unenlightened people of India, Africa and 

 the islands of the sea it is a phenomenon full of terror be- 

 cause of the belief that some great hideous monster is devour- 

 ing the orb of day, but to the astronomer and scienti^^^t it is of 

 such interest and importance that governments, colleges, 

 societies and individuals send out expeditions equipped 

 with costly instruments, over land and sea — literally to the 

 ends of the earth — to locate within the track of the 

 .shadow. 



10 



