TWENTY- THIBD ANNUAL MEETING. 75 



PRELIMINARY OBSERVATION ON THE DESTRUCTIVE BURROWING OF 



SHALE. 



BY O. C. CHAELTON, OTTAWA. 



The shale rocks exhibited were obtained bnt a few hours before the meeting of 

 the Academy. They are completely honeycombed tfy some burrowing animal not 

 yet examined. The tubular cavities are about one-tenth inch in diameter, and, in 

 some of the rocks, so close together that they are too fragile to admit of handling, 

 even gently, without crumbling. Living animals are found only in rocks covered 

 by water. Large numbers of the loose rocks are being thus destroyed. 



PERIODICITY IN PLANTS. 



BY B. B. SMYTH, TOPEKA. 

 I. 



That plants have a regular time each year for leafing, blooming, and fruiting, is 

 a fact well known. From the first blooming of the white elm early in March, or 

 even in February, to the final blooming of the sow thistle (Sonchus asper) in No- 

 vember, there is a constant succession of bloom, and each and every plant passes 

 through the successive steps of its development in its appropriate season. There 

 may be a difference in early spring of as much as thirty days in the first blooming 

 of certain plants, according to the advancement of the season. As the summer 

 progresses the differences of time of first blooming in different years decrease, until 

 in midsummer it is rare to find a difference so great as ten days in the different 

 years; and later in the fall it must be an unusual year indeed that makes even so 

 much of a difference as ten days to occur in the first blooming of a plant at any one 

 place. Hence, in general terms, a late spring, an early fall, and a short growing 

 season, hastens the growth and development of a plant; and a long season retards 

 the maturity and increases the growth of a plant. 



But, generally, plants are so prompt about their motions, such as the opening of 

 leaves and flowers, that an average day may be taken for the first blooming of any 

 individual species, and that particular species will be ordinarily found in bloom 

 within three days from the appointed time, but oftener on the particular day. This 

 refers especially to particular plants in a certain location. 



Not only does each species have its set time for performing its different func- 

 tions, but in any species each different variety has its own time, often differing 

 widely, as in the ripening of apples. Further than that, each individual tree has 

 its own certain time for opening its leaves, blooming, and ripening its fruit, from 

 which it seldom or never varies a day in years haviag equal temperature during the 

 days and months preceding the lookedfor phenomena. For instance: a large male 

 Cottonwood tree in Mr. F. W. Giles's park at the northeast corner of the State yard 

 comes into bloom usually about April 12th, and in four days it has shed all its blos- 

 soms. Two days later, April llth, a large male cottonwood tree in the State yard, 

 between the east wing and the arsenal, opens its blossoms. On the 15th it is fairly 

 magnificent in its wealth of bloom, and two days later it has shed every blossom. 

 Five days later a large male cottonwood in Dr. Gibson's yard, 300 yards distant to 

 the southwest, expands its flowers and for two days is a most beautiful object, and 



