112 ' MICHIGAN ACADEMY OF SCtKNCE. 



cient iHiuiber of specimens I am yet unable to make a definite statement of 

 any of the specific characters. 



The wood is brown or yellowish brown, very heavy and bard, with very 

 large medullary rays with many smaller intermediate ones. The large 

 ducts are collected at the beginning of the season's growth beyond which 

 are arranged the smaller ducts in radial rows. 



First in the red or black oak group the smaller ducts are arranged in 

 single or occasionally double radial rows, the size of the ducts diminishing 

 gradually toward the close of the season. The large ducts are open or at 

 least not abounding in glistening fragments of the original transverse 

 cell walls. 



The white oak group has the smaller ducts arranged in much branched 

 radial rows, the size diminishing abruptly from the larger to the smaller 

 instead of gradually as in the red oaks. The large ducts abound in 

 glistening fragments of broken transverse cell wall which gives the region 

 a silvered appearance. 



In conclusion it may be said that the generic characters of the elms, 

 maples and oaks are very characteristic and may be easily determined 

 with a hand lens. The specific characters, however, are more minute and 

 less distinct, yet are sufficiently characteristic in the instances cited to 

 furnish a reliable guide to timber identification. 



RESPONSE OF ROOTS TO CHEMICAL STIMULI. 



ANNA L. RHODES. 



In the first of this study an attempt was made to determine the effect 

 of a chemical, necessary for plant growth, upon roots growing in a 

 nutritive solution which contained all the essential elements except this 

 one. 



This method admitting of no control of the stimulus applied, since 

 diffusion takes place in no definite manner, the study was varied and 

 different chemical stimuli were applied to the two sides of the growing 

 region of the roots. This was accomplished by using gelatine blocks in 

 which the gelatine was dissolved in solutions of the chemicals of different 

 concentrations. In these latter experiments isosmotic solutions of 

 Ca(N0,)2j KNO3, MgSO^, and NaoHPO^, were used with seedlings of 

 Lupinus albus and Cucurbita pepo. All possible combinations of these 

 chemicals were made, that is, experiments were performed using each one 

 with all the others. It was found that NaoHPO^ was most "attractive" to 

 the Lupinus, and Ca(N03)2 to the Cucurbita seedlings. 



Since the solutions used were isosmotic the possibility of osmotropism 

 is removed. Other experiments in which Ca(N0.)2 and NHjNO;, were 

 used on one side and distilled wafer on the opposite, show that the bend- 

 ing could not be due to a traumatic action of the chemical. 



From these ex])eriments it is evident that chemicals in the soil have an 

 effect upon the direction of growth of roots. 



