297 



In examining the figui'es obtained it is seen there are six species in 

 which the spring -wood tracheides are longer than those of the summer, 

 while seven species have the summer tracheides the longer. The species 

 in each group show variations in hardness and strength, so that taking 

 the length of the tracheides as a factor by itself nothing can be deduced 

 in regard to the quality of the wood, but taking the length and comparing 

 it with the width of the cells, and again comparing the width and the 

 thickness of walls together, and the amount of the spring and summer 

 wood, the strength can be determined within limits in each species. 



For instance, in P. ponderosa scopulorum the spring tracheides are 129.6 

 times as long as they are wide, and the summer tracheides 164.4 times 

 their width, the thickness of their walls is not nearly as great as that of 

 many of the others, but when the thickness is compared with the width 

 of the cells, it is foimd to be fairly thick, and as about two-thirds of the 

 annual ring is summer wood, we have an explanation of the strength of 

 the wood. 



Taking any of these factors alone, it does not mean anything, as the 

 length of the elements may be very considerable, but the width may be 

 also; then, again, the elements may have rather thin walls, if the thick- 

 ness of the wall alone were considered. But when the size of the cell 

 as a whole is taken into consideration along with the thickness, the pro- 

 portion of wall may be greater than the figures representing the thick- 

 ness indicate. 



Contributions to the Flora of Indiana. 

 Stanley Coulter. 



The notes included in this contribution are based, partly, upon a crit- 

 ical study of certain species and partly upon reports and materials sub- 

 mitted by those interested in perfecting our knowledge of the flora of the 

 State. They are presented in the hope that they may prove of interest 

 and value to the botanical workers of the State. 

 Pinus Strobus L. White Pine. 



From Mr. C. F. Very, of New Albany, I have received abundant speci- 

 mens of the leaves and cones of this species with the following notes. 

 The specimens are from tfees planted by the father of Mr. Very some 

 seventy years ago. and one of them is about sixty feet in height, with a 



