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Two experiments were conducted to determine the relative resistance of 33 selected cultivars of English ivy (Hedera helix L.) to soil- and shoot-applied NaCl. In the soil-applied NaCl experiment, ramets of the 33 cultivars were irrigated with a fertilizer + 0.25-N NaCl solution for 55 days. `Harrison', `Hibernica', `Thorndale', Wilson', and Woerner' exhibited the least amount of visible shoot damage. Dry weights of all cultivars were much lower in the salt treatment. In the shoot-applied NaCl experiment, plants were sprayed daily with a 0.25-n NaCl solution for 48 days. The young leaves and stems of all cultivars were severely injured by the salt spray, while the mature leaves and stems and the dormant buds were only slightly injured. Reduction in dry weight varied between cultivars. Two subsequent experiments focused on resistance to soil-applied NaCl. Ramets of the NaCl-resistant `Harrison', `Hibernica', and `Thorndale', and the NaCl-sensitive `Baltica', `Cathedral Wall', and Wingertsberg' were irrigated with a fertilizer + 0.25-N NaCl solution for 48 days. Whole-plant Cl content for all six cultivars was in the range of 30,000 ppm. Ramets of `Thorndale' and `Cathedral Wall' were irrigated with a fertilizer + 0.25-N NaCl solution for 30 days with replicate plants harvested at S-day intervals. `Cathedral Wall' accumulated more Cl at a faster rate than `Thorndale'. Mean whole-plant Cl concentration peaked at 97,000 ppm for `Cathedral Wall' and 40,000 ppm for `Thorndale'. Salt resistance may be partly based on slower uptake of Cl.

A 48-year-old woman developed a crystalline stromal lesion four years after a penetrating corneal graft, with few signs of ocular inflammation. An initial diagnosis of fungal keratitis was made because of the appearance of the lesion. An excisional biopsy revealed the presence of Gram-positive cocci lying between the stromal lamellae in the posterior third of the cornea. Large numbers of Gram-positive cocci were observed on light and transmission electron microscopy but no organism could be cultured from the biopsy. The replacement graft has remained clear over the subsequent two years.

The color of a tree's canopy can provide much information about the tree's physiological status as well as its aesthetic function. We present a system for the qualitative and quantitative analysis of tree canopy color, based on a previously published algorithm. This algorithm determines (with a known accuracy) the Munsell hue, value, and chroma of a color using densitometric readings obtained through the use of color separation filters. This method was adapted for use with black-and-white video images. Combining the Rib algorithm with the techniques of pho- tography, video imagery, scanning microdensitometry, and batch data computer processing, a semi-automated system was devised for the pixel-by-pixel color evaluation of a 512 × 512-pixel image. Based on a sample of 251 color chips, the following accuracies were obtained: Munsell hue — 86%, Munsell value — 93%, Munsell chroma —70%, and Mun- sell color — 62%. An example is provided that demonstrates how this system may be used to determine tree canopy color. By employing this technique, an estimation may be made of the colors and their relative quantities that are displayed by a tree's canopy. The color of a tree's canopy (leaves, flowers, fruit, and branches) can provide useful information on its physiological and pathological condition as well as its aesthetic function. For example, the presence of yellowing leaves may indicate the extent of water stress of a drought-stressed red maple. The se- verity of leaf miner damage on a grey birch might be estimated by measuring the quantity of brown, damaged leaves in the tree's canopy. Similarly, the relative amount of red to green may be proportional to the amount of ripened fruit to leaves present on a cherry tree just before fruit harvest. Likewise, the abundance of white and pink flowers determines the visual ef- fectiveness of a crabapple in bloom. Since canopy color is af- fected by many biological factors, it is not surprising that change in color often is used in scientific studies as an indicator of change in biological condition (Wright, 1969; Paclt, 1983). For the sake of expediency in presenting a paper concerning the measurement of color, a few terms will be defined. Color may be considered as either a quality of light received from an object (the physical definition of color) or a visual experience (the psychological definition of color). Combining the physical and psychological aspects of color, the Munsell color system (Munsell, 1942) is a psychophysical system developed for color determination. A given color possesses the Munsell attributes of hue, value (brightness), and chroma (saturation). In this sys- tem, all colors are arranged according to their attributes into a three-dimensional "color space" known as the Munsell color solid. In an effort to simplify the classification of colors, the Inter-Society Color Council and the National Bureau of Stan- dards (ISCC-NBS) has divided the Munsell color solid into 267 parts (Kelly and Judd, 1955). Each part or category is desig- nated by a name that is descriptive of the colors in that category (examples: white, dark green, very light pink). A technique has been developed to determine the Munsell hue, value, and chroma of a color of a point on a photograph (Rib, 1966). This empir- ically derived method of color determination uses red, green, blue, and amber color separation filters, a densitometer, and a stepwise manual algorithm. We refer to this technique as the Rib algorithm.

The IUCF control system has grown steadily during the first two years of operation. All RF devices and power supplies are almost entirely under computer control so that cyclotron operation is approaching a one man/one chair state. A variety of different areas have seen active development:from sophisticated magnetic field controls to transient suppression in logic power supplies. Analog and digital data isolation for the new 800 kV preinjector is provided by an optical fiber data transmission link utilizing a V/F-F/V conversion scheme. The wide range of beam currents used at IUCF necessitates the use of stable, reliable logarithmic amplifiers and a special antilog routine for the control computer which is both accurate and fast. Energy and particle changes are simplified by using programs to predict appropriate cyclotron operating parameters and to correctly scale older device settings for new beams. Finally, microprocessor systems are being developed to decrease the constantly growing responsibility of the heavily burdened control computer.

1. Projections of pontine visual cells onto the cat cerebellar cortex were studied by antidromic activation and by the retrograde transport of horseradish peroxidase (HRP). 2. Cells in the medial pontine visual area, which receive visual cortex projections, were activated antidromically principally from the contralateral cerebellar hemisphere. Cells in the dorsolateral pontine visual area, which receive an input from the superior colliculus, were activated principally from the vermis and ipsilateral hemisphere. There is some overlap in the projections of these two different populations of pontine cells, which probably occurs by way of bifurcated axons. 3. The HRP technique confirmed that there is a major difference in the pattern of projections from these two pontine visual regions. Many cells in the rostral-medial portion of the pontine nuclei, which receive their input from visual cortex, were labeled following HRP injections in the contralateral cerebellar hemisphere. Far fewer of these cells were labeled following vermal injection. Cells in the dorsolateral pontine nucleus, which receive visual input from the superior colliculus, were labeled following an HRP injection in the vermis or the ipsilateral hemisphere. Cells in the region of pontine nuclei that receive input from the ventral lateral geniculate nucleus were also labeled after a vermian injection. 4. If the vermis is related to the control of whole-body movements and the hemisphere to control of ipsilateral limbs, these results suggest that the corticopontocerebellar and the tectopontocerebellar pathways may be involved in different classes of visually guided movement.

1. Area 18 projects to the rostral pontine nuclei. The visual response properties of rostral pontine cells differ greatly from those that have been reported for area 18 cells. We identified and studied corticopontine cells in area 18 and compared their receptive-field properties to those of other area 18 cells and to pontine visual cells. 2. We first located the visual area in the rostral pons by microelectrode recording and placed stimulating electrodes at the same site. Anti-dromically invaded cells were then recorded in area 18. The antidromic invasion of each cell was verified by orthodromic-antidromic spike collision. 3. Fifty-seven well-isolated corticopontine cells were studied in detail. We also recorded 466 unitary antidromic potentials with a mean invasion latency of 3.5 ms and recorded from 40 additional area 18 units to serve as a comparison group for the corticopontine cells. The comparison group cells were located in the same area in the visual field as the corticopontine cells. 4. The average receptive-field area for corticopontine cells (485 deg2) was much larger than the comparison cells (59 deg2). Forty percent of the corticopontine cells responded preferentially to multiple-spot target. Properly oriented gratings, slits, or edges were the most effective stimuli for the comparison cells. Eighty-two percent of the corticopontine cells showed clear directional preferences to moving-spot stimuli, and downward movements were most commonly preferred. Fifty-five percent of the area 18 comparison cells showed some directional preference, but no particular direction was preferred. The optimal stimulus speeds for corticopontine cells were higher than those for the comparison cells. 5. The response properties of the area 18 corticopontine cells are similar to the response properties of rostral pontine visual cells, except for a somewhat higher selectivity for orientation in the corticopontine cells. 6. We conclude that most response properties of rostral pontine visual cells are already present in a subset of area 18 cortical cells which project to the pons. The corticopontine cells are sensitive to multiple-spot targets moving in particular directions over large portions of the visual field, such properties are consistent with a visuomotor function for the corticopontocerebellar pathway.

1. The superior colliculus projects to the dorsolateral nucleus of the pons. Retrograde transport of horseradish peroxidase (HRP) revealed that cells in the superior colliculus, which send their axons to the pons, lie in both superficial (III) and deep (IV--VII) layers. Superficial cells outnumbered deep cells. The inferior colliculus also projects heavily to the dorsolateral pontine nucleus. 2. Dorsolateral pontine visual cells were activated only by visual stimulation. Cells responsive to somatic or auditory stimulation were also found in the dorsolateral nucleus, and they too responded to only one sense modality. 3. Of the dorsolateral pontine visual cells, 69% were directionally selective. 4. Dorsolateral pontine visual cells were responsive to moving targets over a wide range of stimulus velocities. Velocities between 25 and 100 degrees/s were the most effective. No cells responded to a stationary stimulus. 5. Single-spot targets were the most effective stimuli. Stimulus size was a more important parameter than stimulus configuration. Many cells had inhibitory regions outside of their excitatory fields. 6. The excitatory receptive fields of dorsolateral pontine cells were very large (median, 1,100 deg2). 7. Nearly all receptive fields were centered in the contralateral visual hemifield, and 91% of the dorsolateral visual cells were activated from either eye. 8. We conclude that the visual cells in the dorsolateral nucleus have receptive-field properties that are similar to those of cells in the superior colliculus. The preference of dorsolateral cells for single-spot targets contrasts strongly with the multiple-spot preference of medial pontine cells, which receive their input from visual cortex.