The anomalous complexity of the annual rings of young trees which generally disqualifies them from use in growth studies is, in P. resinosa, found to arise from a remarkably thorough organization of ring width and therefore of cambial activity in the tree under the influence of intrinsic determinants. The pattern is manifest when the widths of the internodal wood rings of a single year are followed in sequence from internode to internode down the tree from the apex. A similarly patterned view of the rings is obtained when the ring widths are traced in the ring sequence, conventional for growth studies, that passes from ring to ring in a given internode. The controlling intrinsic factors are held to be nutritional gradients in the axis inferred from the distribution of foliage and light along the axis of trees growing in the forest and in the open.In both types of sequence the pattern obscures the variations induced by random extrinsic factors and severely limits the value of these sequences for examining the effect of such factors. This disability can be avoided by the use of a third sequence of ring widths in which each term is the width of a ring which was laid down in an internode different but of the same age at the time of ring formation as the others in the sequence. Such sequences have never been used in growth studies. Yet they are found to be unpatterned and the effect of the fluctuating extrinsic factors can be examined effectively in them and in them alone.The complex relation between the responses of the cambium thus determined and those of the apical growing point to the random extrinsic factors is found to derive from the discontinuity of terminal growth introduced by the winter pause between bud formation and axial extension. These two stages of terminal growth are influenced by the extrinsic factors of the two different years. The effect on the cambium is simpler than this but is determinably related to that on the apical growing point.The results afford the ground for a first advance toward the removal of the disqualification of the use of young trees in studies of growth and of its factorial control.

The main shoot apex of P. resinosa is found to comprise four groups of meristematic cells constituting four generative centers by which the parts of the winter terminal bud are laid down. These are the superficial initiating cells, the group or zone of subapical mother cells, the zone of pith mother cells, and the flanking cells.The superficial primordia of the terminal winter bud pass the winter as secondary lateral budlets on the flanks of the main bud axis. Those of the leaf-bearing short shoots do not normally differentiate leaves until the following spring. Neither do those which develop into lateral long shoots. The fertile budlets, on the contrary, produce cones in the late summer and autumn. The female cone enters the winter with no tissue differentiation of the cone body. This takes place very slowly but prominently in the course of the winter. The male inflorescence is well advanced in the autumn and winter progress is relatively slight.The natural control of morphogenesis at the shoot apex including the fitful seeding habit of P. resinosa is considered in the light of the growth timetable. To explain its mechanism, a working hypothesis involving production, consumption, and concentration of auxins is advanced as a preliminary to future work.

Fw0 Ilieasures ;LIT 11i:ecl~d to de~crihe ln~~nlerici~llp the csctivi t y of t h e interiiodal cam1)iuan ill terms of a~lnuaH increnlc~it. 7' 11ese are "specilic wood volrt~lle i~i c r e m~~l t " , a measure of ;~cl t IiCl t oelr ~~i-o(-etlelr-t>s clrld conce~jts n-ere ~I C B I I~ put to the test i 11 illd~xg,cli i~itc-~lsi\.c. I;iiicl will 1 )~ rrelcdetl to ;\c.bic\~c. a falllj, s,ltisf;~c.tor)~ cl:~rific.atio~l of c.vtlia tht> ~r~c'hiiic.~rl ~)i-o%,lc~~ns iiivcslvt~ci iii growtkr studicls oh' this ch,ir;lctcr.In the coursc oi oalr \vtsrl< ~v c a-otlltf 11ot fail to IIC 11111)r~ss~cI 1)). thy cll~iiostirlc-rcclible f,lc-t that tlaoelgha trecLs of geomet ric,ll li;lL,it suc.11 as Y. re~i71u.s(1 it'0111(1 :lpl)car to be ;LIB1OIlg the most ile:~rlj~ idc,~l of livi~ng orgalrisms i l l 1vhic.h t o exanii~ne problems of biologic.:rl growth, j 7 t ' t , the cliornlous litor,~t ur-c1 of t n-c.e growth has c.oriti.ibtiteti little or ~l o t h i~i g to the c o~-a~~) a r ;~t i \~e st url!. of gro~vtla.'I'he reasolr for this wc-~~lld seer...

Although a number of investigators have contributed developmental studies on the Ascomycetes and very substantial progress has been made, our knowledge of the ontogeny of the higher forms of these fungi is still far from complete. In consequence, our present systems of classification are full of gaps, and our conceptions of the affinities of these plants are often contradictory or mere guesses. For the elaboration of a satisfactory system of classification and for the consolidation of our ideas regarding relationships, it is requisite that the ontogeny of a much larger number of representative species be worked out. This investigation has been confined to the Geoglossaceae. Observations have been made on practically complete stages of Cudonia lutea, Spathularia velutipes, and Trichoglossum hirsutum, .and on some of the critical features of Leotia. Heretofore studies in this family have been restricted to three species of the genera Leotia and Mitrula.2 The chief interest centers around Cudonia lutea and Spathularia velutipes because of the remarkable ascogonia possessed by these plants, and because of the conspicuous veils which render obvious to the naked eye their angiocarpous nature, and which have long stood in opposition to the distinction by which SCHROETER3 separates the Helvellineae from the Pezizineae. The youngest stage of Cudonia lutea which has come under observation is in the form of a minute cushion of interwoven threads measuring but 84 l in height. At the center of this loose assemblage of threads may be seen a small but definite group of hyphae which are rendered conspicuous by their size and staining qualities. These are not ascogonia, as might at first be I Preliminary communication. 2 DITTRICH, G., Zur Entwickelungsgeschichte der Helvellineen. Cohn's Beitrage 8: i. i9i8. BROWN, W. H., The developement of the ascocarp of Leotia. BOT. GAZ. 50:443-459. 19IO.

Uniform conditions for the culture of the plants and for conducting starvation–respiration experiments upon the first seedling leaves permit the recapture and hence thorough investigation, of transitory physiological states. A standard sample of isolated, mature leaves, so produced and starved, is shown to be heterogeneous when tested by the tempo at which the tissues in different parts of the sample pass through the color changes that accompany starvation. These are correlated with respiration. Interleaf variation in tempo is relatively small. Intraleaf variation is maximal and the leaf is polarized at isolation but a complex redistribution of tempo within each leaf brings about depolarization and diminishes intraleaf heterogeneity as starvation progresses. The respiration of such a starving sample follows a time course of characteristic pattern, all the prominent features of which have their homologues in the corresponding patterns of younger and older leaves. The homologous characters undergo gradual modification with ontogeny. The respiration of the unstarved isolated leaf is very high and falls rapidly during growth but is low and declines slowly in maturity and senescence. At the transition from growth to maturity a slight, temporary rise in respiration occurs.