THE AMERICAN BOTANIST. 91 



stood what uses many of these structures serve in the economy 

 of plant Hfe, though most of them doubtless aid in modifying 

 the rate of transpiration. 



Injured Sycamores. — Mrs. Emma Buszek writes from 

 Orange, California, in reference to recent notes in this maga- 

 zine on the subject of diseased sycamores, that in California, 

 where the native sycamore is Platanns racemosa, she has noted 

 the leaves affected in a manner similar to that reported for 

 the Eastern tree. There does not seem to have been any in- 

 vestigation made as to the cause of the trouble in the California 

 plant, though it is certainly not due to frost. 



Delayed Germination. — As common and well-known as 

 seeds are, there are still many things about them that puzzles 

 both the cultivator and the scientist. Some will grow as soon 

 as ripe, a few will grow before fully ripe, while the great ma- 

 jority appear to insist upon a season of rest before they will 

 consent to germinate. Usually the renewal of growth, or 

 germination, occurs after a season of drouth or cold has pass- 

 ed, as in our climate the seeds are formed at the approach 

 of winter and germinate when it has passed, but some seeds 

 will not germinate even then and may exist for years in a 

 perfectly dormant state before growth is resumed. In the case 

 of land plants whose seeds behave in this way it has been 

 found that delayed germination is occasioned by the seed 

 coats being impervious to oxygen. Thus denied a sufficient 

 amount of this gas the seeds refuse to grow. Breaking the 

 seed coats to let in the air starts the embryos into growth at 

 once. In water plants a similar condition exists, but Dr. Wil- 

 liam Crocker reports in the November Botanical Gazette that 

 although immersed in water the reason these seeds do not 

 germinate is because they lack not oxygen but sufficient 

 water. Many of them may be kept in water for years without 

 germinating, if care is taken to prevent fermentation. As 



