622 BACTERIAL DISEASES OF PLANTS 



mescences due to chemical and mechanical injury or to frost 

 where clearly there is always some initial loss of water and in 

 some instances, at least, increase of acidity; and finally, of tera- 

 tomas in animals where nothing is known as to cause but where 

 the consensus of expert opinion appears to be that the totipotent 

 or pluripotent cell or cells giving rise to the fetal fragments dates 

 from embryonic time, and in case of the atypical forms although 

 "out of place," would have continued dormant but for the shock 

 of the developing cancer. 



33. In this connection one thinks also of the various processes 

 used by gardeners to hasten the pushing of dormant buds. 



In 1885 Dr. Hermann Miiller-Thurgau showed conclusively 

 that potato tubers of varieties which ordinarily do not sprout 

 until spring can be made to germinate in autumn or early winter 

 by exposing them on ice for a number of weeks. If they are 

 then removed and placed under conditions suitable for growth 

 the dormant buds immediately begin to grow. He showed that 

 potato tubers placed under these conditions change a portion of 

 their starch into sugar and he believed that this increase of 

 sugar is the cause of the germination. He mentioned incident- 

 ally that there is also an increase of acid but lays no stress on 

 this increase which, however, I believe to be the actual cause. 

 His chilled potatoes which had become sweet were twice as acid 

 as the unchilled ones (3.14 pro mille reckoned as malic acid, as 

 against 1.74). 



In 1900 Dr. W. Johannsen, the Danish physiologist, experi- 

 menting at first with sulphuric ether discovered that a great 

 variety of plants which ordinarily do not push their winter 

 buds until spring can be induced to push them in late autumn 

 or early winter by etherizing the plants or by chloroforming 

 them. Lilacs, for example, by this method can be brought into 

 blossom at Christmas time and willows can be induced to push 

 their catkins in autumn within a week or ten days of the time 

 they have been anesthetized. This method of procedure, 

 worked out in detail by Johannsen for a variety of plants, proved 

 so dependable and profitable that it is now used by florists the 

 world over. The dose, temperature and time for lilacs is as 

 follows: 30 to 40 grams of ether per hectolitre of air space 



