216 PRACTICAL LESSONS IN SCIENCE. 



tree. The cones are small, about two inches in length, the free 

 ends of the scales being produced into protuberances, which are 

 sometimes recurved. The Austrian pine has longer leaves of a 

 dark green color, without powder. The Cones are much larger, 

 but without the recurved protuberances. 



As plants vary considerably during the growing season, a com- 

 plete study necessitates continuous observation during the inter- 

 val between fertilization and maturity, with a study of every 

 phase of growth ; or specimens of the different stages of develop- 

 ment may be collected and preserved in alcohol, so that the study 

 can be made at any time of the year. 



The male flowers of the Scotch pine form a catkin or spike-like 

 cluster at the base of the young shoots, and should be gathered 

 for study in May or June. The female flowers form inconspicuous 

 clusters toward the end of the young branches. Specimens should 

 be gathered as above, and later in the season also. Leaves and 

 stems and young cones, found just below the new shoots, should 

 be gathered in July or August, and the terminal buds and mature 

 cones in late autumn. Fresh leaves and stems may be used at 

 any time, but the resin which abounds in fresh material often 

 makes it unpleasant to work with. 



In studying the pine notice the central shaft or trunk of 

 the tree, extending without division to the very summit. Note 

 the whorls of branches at definite places on the stem, and 

 also the angle they make with the main stem, and compare the 

 pine with other kinds of trees in these respects. . In young trees 

 or branches of older trees note the difference in vigor between the 

 terminal and lateral shoots. Make cross sections of the smaller 

 stems and branches, then counting the rings of growth, notice if 

 there is any relation between the age of the stem and the number 

 of whorls of branches. Note the short branches bearing the pairs 

 of green leaves, pull out the leaves and then from the scars study 

 the numerical arrangement, also study the arrangement of the 

 scales on a mature cone and compare the two. Notice the surface 

 of the youngest shoots, then following the branch back to the 

 main stem note any changes as to bark, scales, etc. 



