196 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



showed three well-defined zones for 1944 tip growth although they 

 were not separated by terminal bud scale scars. The inner zone, the 

 longest of the three, bore leaves which were set 5 or more cm. apart. 

 The middle zone, up to 19 cm. long, was bare and the "undeveloped 

 leaves" set close together, i to 2.5 cm. apart. On the outer zone, 7.5 

 to 10 cm, in length, the leaves were set 5 or more cm. apart. Thus, 

 based on observations and measurements, the inner and outer zones 

 represented intervals of rapid tip growth whereas the central zones of 

 slow growth were equivalent to the level of terminal bud scale scars 

 on other branches which had two distinct tip flushes, such as WCh 2-4, 



Branch WCh 2-5 is a specific example of a transitional growth type 

 between continuous growth and intermittent growth with definite ter- 

 minal bud scale scars. In the 1944 tip growth, the inner zone of 22 

 cm., bore leaves and twigs far apart; the middle zone of 19 cm. bore 

 only "undeveloped leaves" which were close together; and the outer 

 zone of 10 cm. bore leaves and twigs far apart except near the tip, 

 where the distances decreased. No terminal bud scale scars appeared 

 within the 1944 tip. Sections a from the inner zone of 1944 contain 

 I see plus arcs of diffuse densewood for 1944 and the same for 1945. 

 Sections b from the middle zone of 1944 contain i see for 1944 and i 

 see for 1945. Under the wide-field binocular, unstained sections show 

 probably three growth layers. Sections c from 1945 tip growth con- 

 tain I see plus I dee, all of which under the wide-field binocular shows 

 as two growth layers. It is quite possible that the arcs of 1944 sections 

 a correspond to the growth slowdown represented by the 19-cm. 

 middle zone. On the contrary, 1945 sections a also contain arcs, but 

 their definition could not compare with that of the arcs in 1944. WCh 

 2-5 illustrates the uncertainty of interpretation using unstained sec- 

 tions and low magnification ; it also illustrates a transitional growth 

 type. 



The peach tree, WPe i, possessed two types of elongation for sec- 

 ond tip flushes in one year, an "offset flush," or the substitution flush 

 of Ratzeburg (1866), and an "in-line flush," In the first case, the 

 original growing tip died and withered because of sun scald or insects, 

 and a new tip emerged from the first axillary bud back of the withered 

 tip. These are second flushes in a certain sense, but do they have an 

 accompanying effect in the xylem? In the second case, later flushes 

 of the same season continued growth outward from the original tips 

 and were separated therefrom by terminal bud scale scars, 



WPe I -I, cut off January 21, 1945, had two offset twigs which arose 

 from the first two axillary buds back of the withered tip of the first 

 flush. Sections were taken from the first flush and from each of the 



