BREVITIES. 163 



nation plant through its stomas, or through insect piercings, it 

 quickly ceases to be a local and becomes a constitutional disease. 

 If mosquitoes distribute the germs of yellow fever, aphides can 

 carry and inoculate plants with the germs of rust. Whether they 

 do or do not, it is patent to observing carnation growers that their 

 vaccinating punctures are followed with the pathology of "Rust." 

 Rust is no more a local disease than is scrofula. The animal 

 may have a scrofulous diathesis, the plant a rust diathesis. A 

 scrofulous gland may be cut out or a joint amputated, and it in 

 nowise disturbs the constitutional disease. Diseased leaves on 

 a rust plant may be picked off as fast as the}^ appear, and it in 

 nowise affects the fatal progress of the disease after it becomes 

 constitutional. 



The rapidity with which this micro-organism multiplies itself 

 is shown by the following extract from bulletin 59 of the A. E. 

 Station, Purdue University. 



"We may conclude from these observations that under good 

 conditions for growth an individual of Badeiiiim Diajithi may be- 

 come two within a half hour, and these two increase to four in 

 the second half hour, and so on. At this rate there would be 

 sixteen at the end of two hours, sixty- four at the end of three 

 hours, 256 at the end of four hours, over sixteen million at the 

 end of twelve hours and over 280 billions at the end of one day. 

 Is it any wonder that a few germs placed in a test tube culture 

 will make it turbid within twenty- four hours? Although the 

 individual bacteria are very minute, requiring 1500 of them 

 placed side by side to extend the sixteenth of an inch, yet the 280 

 billions that may be formed from one germ within a day represent 

 no insignificant bulk. They would in fact occupy fully a cubic 

 inch of space. As it takes the material of three or four fluid cul- 

 tures to fill a cubic inch, it is evident that even under the favor- 

 able condition of artificial cultivation the food supply soon be- 

 comes inadequate to keep up a maximum rate of growth." 



