286 



Annual Report for 1912 of the Botanist. 



A word or two of explanation regarding the interpretation 

 of seed analyses may be of value. The tests carried out in the 

 department are usually stopped as soon as they have shown that 

 the germinating capacity is equal to that demanded on the 

 Society's order forms. Where detailed analyses, for comparison 

 with seedsman's guarantees, are required, the fact should be 

 mentioned at the time of sending the samples. Such a course 

 may save re-testing and a considerable delay, for in the case of 

 some grass seeds, tests have to be kept running for forty-two 

 days before there is any certainty that no more seeds will 

 germinate. In the event of the analyses showing a lower ger- 

 minating capacity than the guaranteed figures, some allowance 

 must be made to cover possible errors of observation. It must 

 be remembered that it is practically impossible to draw an 

 absolutely representative sample from bulk and wdien the sample 

 has to be further reduced to four hundred or six hundred 

 seeds for a germination test, a second and probably larger 

 sampling error creeps in. To cover this the following " latitudes " 

 are generally recognised as allowable : — 



Percentage of germination 

 between 

 99-9 —95 per cent. 

 94-99—90 

 89-99—85 

 84-99—90 

 79-99—75 

 74-99—70 

 69-99—65 

 64-99—60 

 59-99—55 

 54-99—50 



"Latitude" 

 percentage 



4-2 



5-7 



6-8 



7-7 



8-S 



8-8 



9-1 



9-4 



9-4 



9-6 



that it will show a 

 sis shows that it is 



If then seed is bought under a guarantee 

 germination of 75 per cent., and the analy 

 1 per cent, lower, it may well be assumed that the sample is 

 substantially what it was represented to be. 



During the season 1911-1912 very few objections had to be 

 raised with regard to the germinating capacity of members' 

 seed samples. A few analyses have been made of the seed 

 available for the coming season, and so far as there have been 

 opportunities of forecasting its quality it seems probable that 

 some of it will prove unsatisfactory. The samples of wheat and 

 barley tested up to the present show a considerably impaired 

 germinating capacity, and oats, which have had to contend 

 with a severe frit-fly epidemic, as well as bad harvest conditions, 

 may well prove strikingly deficient in this respect. 



The enquiries with regard to the management of grass land 

 during the past season have been of more than ordinary 

 interest, as they show very clearly the after effects of the 

 prolonged drought of 1911. On many types of soils, but more 



