NOTES AND ABSTRACTS. 



623 



After-ripening occurs with drying of the seed, but is independent 

 of it, for the percentage of germination in air-dried seeds soon after 

 harvest is lower than it is in spring for seeds with the same v/ater 

 content. 



Light does not affect germination. — G. F. S. E. 



Germination Power of Seeds. By Marvin L. Darsie, Charlotte 

 Elhott, and George J. Peirce {Bot. Gaz. Iviii. pp. 101-136, Aug. 1914 ; 

 18 figs.). — The authors refer to the length of time during which seeds 

 may retain their power of germination, the oldest known cases 

 being three seeds of Cassia which germinated when eighty-five years 

 of age. The majority of seeds of cultivated plants cannot survive one 

 year of burial in earth, as shown by certain experiments at Washing- 

 ton, though many weed seeds showed but little deterioration in that 

 time. 



The numerous experiments given in this paper were intended to 

 test whether the temperature in Dewar's flasks in which seeds were 

 germinated could be taken as a test of their germinating power or of 

 their viability. 



The authors found that each species had, like the higher animals, 

 a normal temperature. When the temperature was in excess of the 

 normal it was usually found that the seeds were infected by fungi. 

 Subnormal temperature indicated lessened vigour. Increased age 

 very generally resulted in decreased vigour. 



The average daily heat yield in terms of ten grams of seeds varied 

 as follows : — Indian corn '49 C., oats '55, v/heat 73, clover 75, 

 barley '88 and hemp 1-82. — G. F. 5. E. 



Gooseberry Mildew, Control of. By G. C. Gough [Gard. Chron. 

 November 7, 1914, p. 303, and November 14, p. 319). — Discusses 

 four methods. 



1. Destruction of infected plants, which is shown to be unnecessary 

 except where percentage of infected plants is not high. 



2. Spraying is generally too costly. Conidia being released 

 throughout the growing season, infection may be as constant as growth. 

 Where only recently infected it may serve a good purpose. 



3. Treatment of soil. Lime hoed in in March has been found to 

 do good. 



4. Removal of diseased tips. This is the best course to pursue. 

 Best done late enough to insure no fresh growths being made, in most 

 seasons in September. If it makes bushes too dense, the centre should 

 be kept open. — E. A. B. 



Graft Hybrids from a Cytological Point of View. By J. N. 

 Martin {U.S.A. Hort. Soc, Iowa, Trans. 1913, pp. 161-166). — The 

 writer discusses three types of phenomena arising through grafting 

 which are often designated as graft hybrids — anomalous plants arising 

 as adventitious branches from the wound callus, modifications of the 



