LOCALIZED STAGES IN DEVELOPMENT. 113 



siderecl as the more primitive of our New England species. In tlie Live Oak of California 

 [Quercus chrysolejns Lieb.),the Laurel Oak (Q. imbriearia Mich.) , and the Oblong-leaf 

 Oak {Quercus oblongifolia Torr.), according to Professor Sargent ('91-97) , the typical 

 leaves are entire, Iseing oval, oblong, or lanceolate in the several species. In vigorous 

 shoots (also in the young of Q. chrysoJepis), he says the leaves are often dentate or 

 lobed. These and similar species at first sight appear to be primitive oaks, on account 

 of the simpUcity of their leaves, which in general are comparable to the simple leaves of 

 fossil species and the young of specialized species. As vigorous shoots so frequently 

 show reversionary characters, it suggests the view that these species may be simple from 

 reversion not from primitiveness. A study of oaks from this point of view w'ould be 

 interesting. 



MvRicA CERiFERA. Seedlings of the Bayberry [Myrica cerifera\j.) , yvavQ obtained 

 from the Arnold arboretum. The cotyledons (PI. 19, figs. 52, 52a) are broad, spathulate, 

 distally emarginate, non-petiolate, 5.5 mm. long, 3 mm. wide. The first nepionic leaves 

 are 6 mm. long, 4 mm. wide, broadly spathulate, with three distal dentations. The first 

 four leaves are of the same form only increasing in size. In later leaves additional mar- 

 ginal indentations develop so that the leaf has a slightly lobate border; also a petiole 

 develops, the blade extending down the petiole marginall}^ 



In the adult the leaves are very variable, being entire or slightly toothed (PI. 19, 

 fig. 53). The midrib always extends at the tip as a slight mucronate point, in this 

 feature resembling the tip of the eai-ly nepionic leaves. Very fre(^uently two ter- 

 minal indentations occur, when the leaf may be closely compared with the first nepionic 

 leaves ; frequently more indentations occur when in this feature it may be compared mth 

 later leaves of the seedling. As a whole it may be said that the later leaves of tlie seed- 

 ling are more deeply dentate and in this character more specialized than the leaves of 

 the average adult. 



PiNUS EiGiDA. The Pitch Pine (Fbins rUjkla Mill.) presents interesting localized 

 stages. In the seedling the cotyledons are strong and vigorous (PI. 21, figs. 72, 73) . 

 They vary in number from four to seven. In 10(J seedlings counted, 18 had 4 cotyledons, 

 55 had 5 cotyledons, 26 had 6, and 1 had 7. Lubbock ('92) says tliat the Pitch Pine has 

 from 4 to 6 cotyledons. The seven cotyledons found in one specimen are evidently some- 

 what i-are, and may be anomalous for the species. The cotyledons are smooth and free 

 from spinose growths, they are roughly triangular in section (PI. 21, fig. 73b), and 

 acinninate distally. The form of these cotyledons is attributed to tlieir mutual contact 

 and pressure during growth ; compare PI. 21, fig. 73b, with the White Pine cluster (PI. 

 21, fig. 81a, b), where five leaves are brought close together during growth, inducing a 

 similar triangular form. Succeeding the cotyledons, the young Pitch Pine is densely 



