\ (tOODEY 



•in 



denco of attack by Ti/lenr/nis would be due to differences of suscepti- 

 bility to the jtarasite. That this was a reasonable and sound assumption 

 is borne out, I think, by the results obtained. 



On July 8th, that is, after 37 days, all the seedlings were harvested, 

 counted, and after being separated into deformed and health}' in ap- 

 pearance, were separately jiickled in 70 per cent, alcohol. 



The figures obtained in this way enabled me to arrive at Ihe per- 

 centage of deformed seedlings in each case, as shown in the following 

 table. 



Taljle [. Showing Ihe ninnherf: of heallhi/ (uul ilcfunned nvedlinys, 

 ihe percenlage of (leforined, and Ihe sliindard error. 



No. of .seedling's 



' , i'ciri'ntage of Stiiudiiiil 



Trefoil 



41 



41 



These figures of ]iercentage infection give one a rough indication of 

 the susceptibihty of the different kinds of clovers, etc., but it was 

 thought that if one could estimate the numbers of Tylenchus in a series 

 of deformed seedHngs one would be able to arrive at some expression 

 for the intensity of infection or intensity of susceptibihtv in eacli case. 



With this end in view I examined all the deformed seedlings and 

 selected the ten most deformed in each case, and then proceeded to the 

 dissection of these in order to obtain the contained Tylenchus. 



Each seedhng was carefully dissected by means of needles, with the 

 aid of a binocular dissecting microscope. This, of course, was a slow 



