1895.] and allied Plants known as "Finger and Toe'' <Jr. 331 



soil containing lime the disease was absent. This opinion is cor- 

 roborated by the same author at a later date.* 



The following is an account of experiments conducted during four 

 successive years at Kew. 



1. Healthy seedling cabbages planted in soil that had two years 

 previously produced a crop of diseased cabbages, became diseased. 

 Check plants from the same batch of seed, grown in sterilised soil, 

 remained free from disease. Somervillef has also demonstrated 

 that turnips become diseased when the seed is sown in soil brought 

 from an infected area. 



A. Experiments conducted in a Sterilised Solution of Stable Manure. 



2. The contents of two flasks were infected by adding crushed 

 tubercles of a diseased cabbage root. 2 per cent, of a saturated 

 solution of potassium hydrate was added to the contents of one flask, 

 and 2 per cent, of commercial sulphuric acid to the other. A young 

 cabbage plant free from disease was then placed in each flask. At 

 the end of two months the plant in the flask containing potassium 

 hydrate was growing vigorously and perfectly free from disease, 

 whereas the plant growing in the solution containing sulphuric acid 

 was badly diseased, much more so than check plants growing in 

 infected soil free from acid, for the same period of time. Similar 

 experiments made during successive years always yielded the same 

 result. 



3. Two young cabbage plants showing decided symptoms of disease 

 were placed in flasks containing the same proportions of potassium 

 hydrate and sulphuric acid respectively as in Experiment 1. At the 

 end of two months the plant growing in the solution containing 

 potassium hydrate appeared to be perfectly healthy, the indications of 

 nodules present on the root at the commencement of the experiment 

 having become effaced by subsequent growth. The plant growing 

 in the solution containing sulphuric acid was badly diseased. 



Similar results were obtained in Experiments 1 and 2, when potas- 

 sium hydrate was replaced by ammonium hydrate, and sulphuric 

 acid by hydrochloric acid. 



4. Two diseased seedling cabbages were placed in separate flasks of 

 the sterilised solution. The liquid in one flask was saturated once a 

 week with carbonic dioxide, the contents of the second flask not 

 being interfered with in any way. At the end of two months both 

 plants had the disease developed to the same extent, proving that 

 carbonic acid is neutral as regards the development of Plasmodio- 

 phorce. 



* Op. tit., Ser. Ill, vol. 5, p. 321 (1894). 

 f Op. cit., Ser. Ill, vol. 5, p. 808 (1894). 

 VOL. LVII. 2 B 



