THE REST-PERIOD OF SEEDS 427 



The problem, however, is an extremely complex one. A 

 method of approaching it is indicated in Chapter XIV, where 

 it is shown that two types of fruits can be differentiated when 

 we deal with the proportions of parts for the successive stages 

 of the fruit, as tabulated on p. 303. But this ignores the 

 transition from the albuminous to the exalbuminous state of 

 seeds, which involves a factor of paramount importance, and 

 one that carries us back to a very early state of the seed's 

 development. The whole subject will acquire a very com- 

 plicated character when we introduce this consideration into 

 the discussion. 



A chance observation in May 1908 led me to suspect that The winter 

 the embryo of the seed of the Ivy (Hedera Helix) grew con- fhe embryo 

 tinuously through the winter and that germination occurred 

 without any rest-period in the spring. My suspicion was to plant 

 some extent confirmed when I found early in June that many 

 of the embryos had nearly doubled their length since the last 

 observation, and that some seeds were germinating within the 

 fruit on the plant. However, the actual growth of the embryo 

 in the winter had yet to be established. To this end my 

 sister, Mrs H. Mortimer, made periodical collections of the 

 berries at Redland, Bristol, during the winter 1908-9 ; and 

 on my return to England from the West Indies in the spring 

 I made use of these materials, the principal data obtained from 

 them being incorporated in the table subjoined. The behaviour 

 of the embryo in the spring was observed by me during the 

 four years, 1908-11. 



It will be seen from the results tabulated on p. 428 and The growth 

 from the accompanying figures that the berries increased embryo of 

 gradually in size from the beginning of November 1908 to the jjj^jf upt< 

 latter part of January 1909, the green colour giving place to a 

 blackish hue and the maximum growth corresponding to the 

 complete blackening of the fruit. The increase during this 

 period of the solid constituents of the growing fruit as the 

 water-percentage diminished is especially noteworthy. Up to 

 January also the seeds grew with the fruit, their increase in 



