TIME RELATIONS OF GROWTH : III. GROWTH CONSTANTS DURING THE SELF-ACCELERATING PHASE OF GROWTH.

Growth curves consist, in all cases, of two major segments. The first major segment is, in the case of higher animals and plants, made up in turn of several (probably five) shorter segments during each of which growth takes place at a constant percentage rate. The transitions between the successive stages are abrupt, the abruptness being of the order of metamorphosis in cold blooded animals. It has been made clear in the first paper of this series that the time rate of growth following the major inflection declines at a constant percentage rate. The junction between the two major segments occurs at puberty in animals and flowering in plants. The two major segments are not symmetrical about the major inflection. The slope of the segment following the inflection is always less than the slope of the segment preceding the inflection. The major inflection does not occur in the center of the growth curve. The instantaneous rate of growth at the beginning of growth is of the order of 100–200 per cent per day (i.e. the body weight is doubled in from 7 to 17 hours). It may be mentioned that 2 months after conception the rate of growth in man is only 8 per cent per day. This is contrary to all the published statements. Thus, Minot concluded that growth begins at 1000 per cent per day; Jackson concluded that in man, growth during the 1st month takes place at 57.5 million per cent per month; during the 2nd month 990 per cent per month; during the 3rd month 390 per cent per month (8 per cent per day is only 240 per cent per month). The reason for the discrepancy between the values derived, by the method adopted by the writer, and the values given in the literature is explained by Fig. 1.     

TIME RELATIONS OF GROWTH : I. GENETIC GROWTH CONSTANTS OF ANIMALS.

This paper is the first in a series proposing to evaluate growth constants from the viewpoint of and by the methods of the physical chemist. After discussing the physicochemical conception of growth, tentative numerical values of two growth constants are given for several species of animals including man, and the methods of computation are discussed in detail.     

SEEDLING GROWTH STUDIES OF EARLY-RIPENING PEACHES. I. INTERRELATIONSHIP BETWEEN EMBRYO MATURITY,GROWTH SUBSTANCES AND SEEDLING GROWTH

Weaver , Gerald M., and L. Fredric Hough . (Rutgers, The State Univ., New Brunswick, N. J.) Seedling growth studies of early-ripening peaches. I. Interrelationship between embryo maturity, growth substances and seedling growth. Amer. Jour. Bot. 46(10): 718–724. Illus. 1959.—Peach fruits of ‘Raritan Rose’ were harvested 75, 83, 91, 99 and 107 days after full bloom. Embryos were excised, and cultured on artificial media. Growth responses following 8 wk. cold treatment varied considerably with embryo maturity. No correlation existed between seedling survival and the initial responses of shoots. Root growth of 83-day embryos exceeded that of all other stages of maturity. This was reflected in maximum seedling survival and vigor. Initial shoot growth was greatest from embryos harvested at 91 days and at maturity (107 days), but all shoots developed into rosettes which may expand slightly or develop normally from axillary buds. Bioassays of growth substances suggest a strong correlation between early shoot development and auxin concentration. Root growth-responses appeared to be correlated with a promotor-inhibitor balance. The results of wheat coleoptile assays of embryo extracts chromatographed in an isopropanol: ammonia: water solvent (8:1:1) suggest the presence of three growth promotors, in greatest concentration at Rf 0.70, but also at Rf values 0.10 and 0.30. Two growth inhibitors were present in embryo tissue at Rf values 0.27 and 0.96, the former decreasing in concentration with increasing embryo maturity.     

PATTERNS OF GROWTH IN BIRDS. II. GROWTH RATE AND MODE OF DEVELOPMENT

This analysis was initiated to examine the relationship between the rate of growth in birds and their development of mature function. The literature was surveyed for data on growth and development, and the growth curves of 81 species were chosen for the analysis. Growth curves of most species were fitted with the Gompertz equation, and the rate constants of the equation were used as an index of the growth rate. For those species whose curves were fitted better by other equations, with a slightly different form, appropriate conversion factors, derived in this paper, were employed.
Among species with similar modes of development, growth rate decreases with increasing body weight in an allometric manner, with slopes of –0.26 to –0.42, depending on the group. Between groups, the rate of growth in body weight was found to be closely associated with the rate of development of function, in particular, the acquisition of flight. Among those species that can walk at an early age, but acquire flight relatively late, the rate of growth depends primarily on the relative size of the musculature of the lower extremities.
Data are presented to refute the hypotheses that growth rate is adjusted to nestling mortality, or that the energy requirements of the young (and hence their growth rates) are balanced against brood size. It is concluded that most species grow at some physiologically maximum rate, but as yet it is not possible to distinguish between limitation of growth rate at the level of the organism or at the level of the tissue.     

THE PHOTOINHIBITION OF GROWTH IN ETIOLATED STEM SEGMENTS. II. GROWTH CAUSED BY COBALT IN PISUM

Bertsch, Walter F. (Yale U., New Haven, Conn.) The photoinhibition of growth in etiolated stem segments. II. Growth caused by cobalt in Pisum. Amer. Jour. Bot. 50(3): 213–219. Illus. 1963.—Etiolated pea stem sections were utilized to study the effects of various metal ions on the red, far-red photoinhibition of stem growth. Excision of immature tissue results in loss of photosensitivity. All growth caused by cobalt, either in the presence or absence of sugar, was inhibited by brief exposure of the excised tissue to red light. Since growth caused by sugar is also light-sensitive, it may be said that either cobalt or sugar may induce photosensitivity in this immature tissue. Other divalent metal ions were tested, but only nickel promoted growth. Although cobalt and nickel showed the same optimal concentration (ca. 2 × 10⁻⁵ m), growth caused by nickel was not photosensitive, suggesting that cobalt and nickel promoted growth through separate mechanisms. Since growth caused by indole-3-acetic acid or gibberellic acid is also insensitive to light in this tissue, a photosensitive sugar-cobalt growth system has been experimentally separated from other growth-controlling systems. The photoinhibition of a growth system which utilizes sugars and is promoted by cobalt and the relation of this system to certain de-etiolation phenomena are discussed.     

THE RATE OF GROWTH OF THE DAIRY COW : EXTRAUTERINE GROWTH IN WEIGHT.

The growth period of the Jersey and Holstein cows is made up of at least three cycles, two extrauterine cycles with maxima at about 5 and 20 months of age, and one intrauterine cycle, the maximum of which has not yet been determined. The equation of an autocatalytic monomolecular reaction was found to give very good results when applied to the cycle having its maximum at about 5 months of age. The values obtained from this equation when applied to the cycle having the maximum at about 20 months of age were higher than the observed values probably due to the retarding effect of pregnancy and lactation on growth.     

THE RATE OF GROWTH OF THE DAIRY COW : V. EXTRAUTERINE GROWTH IN LINEAR DIMENSIONS.

Barring fluctuations due to the cyclic phenomena, the extrauterine course of growth in linear dimensions and in weight of the dairy cow follows an exponential law having the same form as the law representing the course of monomolecular change in chemistry. This suggests the interpretation that the general course of growth is limited by a monomolecular chemical process, and that the cyclic phenomena are due to subsidiary processes in the fundamentally exponential course of growth. The fact that growth follows or tends to follow an exponential course may be stated more simply as follows: if the unit of time is taken sufficiently large so that fluctuations due to the cyclic phenomena are balanced or eliminated, then the amount of growth made during the given unit of time at any age tends to be a constant percentage of the growth made during the preceding unit of time. Thus, the growth in height at withers made during any year is about 34 per cent of the growth made during the preceding year. Similarly the growth in weight made during any year is about 56 per cent of the growth in weight made during the preceding year. This is in accordance with expectations if it is assumed that each animal begins life with a definite endowment of limiting substance necessary for the process of growth, and that this endowment is used up at a constant rate (or percentage) of itself.     

鱼腥藻1017株的混合营养型生长

鱼腥藻１０１７株混合营养型生长有其特点,外源葡萄糖对生长的刺激不仅在低光强（８００ｌｘ）,而且在高光强（７０００ｌｘ）也表现出来。其混合营养型生长速率在８００－７０００ｌｘ范围内随光照强度的增加而增加,在葡萄糖浓度５－２０ｍｍｏｌ／Ｌ范围内随外源葡萄糖浓度增加而增加。鱼腥藻１０１７株混合营养型生长与光能自养生长相比,生长速率明显提高,对数生长期延长,收获物浓度显著增高,生物量显著提高。     

GROWTH AND ORGANIZED DEVELOPMENT OF CULTURED CELLS. V. THE GROWTH OF COLONIES FROM FREE CELLS ON NUTRIENT AGAR

When angiosperm cells are cultured in a liquid medium they may grow in the form of free, single cells and form small to large groups of cells. This has been shown in earlier papers. This paper deals with the growth of strains of cells (Daucus carota and Haplopappus gracilis cells were used), washed and filtered free from the larger groups, on nutrient agar media in Petri dishes, thus simulating familiar microbiological technique. Each discrete member of a suspension is referred to as a “unit.” On the order of 1–10% of the separate units of a suspension may be induced to grow into viable colonies, depending on the strain and the conditions employed. Whereas at least 30% of the free single carrot cells were shown to be capable of division, only up to about 4% continued their growth to form macroscopically visible colonies when they were widely dispersed. Coconut milk promotes the growth of carrot cells into colonies. Both coconut milk and napthaleneacetic acid, which interact synergistically, arc required for the growth of Haplopappus cells. Various techniques which affect viability (the frequency with which units grow into colonies) were investigated. The viability of carrot units was found (1) to increase with their density on the plates; (2) to decrease upon washing the suspensions prior to plating; (3) to increase with increasing initial size; and (4) to decrease to a vanishingly low value in rigorously filtered suspensions which consist principally of single cells, although the single cells were found to grow with appreciable frequency when the larger units were also present; and (5) to increase dramatically (100-fold) when a rigorously filtered suspension was plated on a medium upon which pieces of growing cultured tissue were placed. Thus, the induction of growth in free cells is enhanced, even in an environment nutritionally optimal for the growth of the larger cell masses, by as yet unknown factors which are contributed by the cells themselves, or by adjacent cells or groups of cells. It is suggested that within a group of cells growing in culture, and perhaps also in the organized growing regions of intact plants, the dividing cells are nourished or stimulated by adjacent but less frequently dividing cells. The implications of these results are discussed.     

GROWTH REGULATION BY ETHYLENE IN FERN GAMETOPHYTES. I. EFFECTS ON PROTONEMAL AND RHIZOIDAL GROWTH AND INTERACTION WITH AUXIN

Three responses resulted from the treatment with ethylene of dark-grown gametophytes of Onoclea sensibilis. Elongation of the filament was increased, elongation of the rhizoid was decreased, and cell division was inhibited. The optimal ethylene concentrations were between 0.01 and 0.1 ppm. Filament elongation was very tolerant of high ethylene concentrations, since up to 1,000 ppm did not inhibit growth below control levels. Enclosing cultures of gametophytes in chambers of limited volumes produced all the effects of treatment with ethylene, but the responses to sealing were eliminated if plants were enclosed in a chamber which contained a solution of mercuric Perchlorate. This evidence that gametophytes produced ethylene was substantiated by a direct gas chromatographic demonstration of ethylene formation. The growth-regulating effects of ethylene and auxin appeared to be independent in filament and rhizoid growth. Inhibition of elongation by supra-optimal auxin concentrations could not be attributed to an auxin-stimulated production of ethylene.     

APICAL GROWTH OF PROTONEMATA IN ADIANTUM CAPILLUSVENERIS. I. RED FAR-RED REVERSIBLE EFFECT ON GROWTH CESSATION IN THE DARK

Apical growth of individual protonemata in Adiantum capillus-veneris was microphotographically observed before, during and after light treatment. When single-celled protonemata precultured under continuous red light were transferred to darkness, the apical growth continued for the next 24 hr at a rate somewhat slower than that under continuous red light, but the rate significantly decreased thereafter and growth ceased within 72 hr in the dark. The growth in the dark was strongly inhibited by a brief irradiation with far-red light given immediately before the dark period, and the effect of far-red light was fully reversed by subsequent red light. This reversibility was repeatedly observed, suggesting the involvement of a phytochrome system.
The intracellular localization of the phytochrome system in the protonemata was studied, using a narrow-beam irradiator. The results showed that the photoreceptive sites of far-red light are not localized in any particular region of the cell.