Increase In Mean Length Research Articles

Size-Related, First Winter Mortality of Freshwater Fishes

Abstract To determine if first winter mortality were greater for small than for large freshwater fish, we conducted eight experiments in lakes and hatchery ponds during which fish were measured in late fall and early spring. Overwinter increase in mean length of the bluegill, Lepomis macrochirus, in one lake and largemouth bass, Micropterus salmoides, in another could have been caused by higher mortality of smaller fish. Size-related mortality was not detected in six other populations–two of bluegill and one each of largemouth bass, green sunfish, Lepomis cyanellus, fathead minnow, Pimephales promelas, and white crappie, Pomoxis annularis. Available evidence indicates that size-related mortality is probably not a common phenomenon for bluegill and largemouth bass, but it may be important for walleye, Stizostedion vitreum, and sander, Stizostedion lucioperca.

The gestures of a gorilla: Language acquisition in another pongid

A female lowland gorilla, Koko, has been engaged in an ongoing language program since July 1972 when she was 1 year old. During the first 30 months of training she acquired a vocabulary of 100 words in American Sign Language which she spontaneously combined into meaningful and often novel statements of up to 11 signs in length. The gorilla is using a rapidly expanding vocabulary of signs to express semantic and possibly grammatical relations similar to those expressed by human children in the early stages of language acquisition. Patterns of generalization, gradual increase in mean length of utterance, and innovative use of gestural language are discussed in relation to data available on children and chimpanzees.

Latitudinal Variation of Pacific Herring Fecundity

Abstract Fecundity relationships of 156 female herring (Clupea harengus pallasi) from Prince William Sound were studied. Upon comparison with other North American populations of Pacific herring, we found a progressive decrease in fecundity at a particular body size with increasing latitude. We also found an increase in mean length and mean fecundity of spawner with latitude.

Diameter, length and branching ratios in the bronchial tree

This paper is concerned with morphology and pattern of branching in the bronchial tree and their interrelationships. Branching ratio (R b), diameter ratio (R d), and length ratio (R 1) are the factors by which the number of branches, mean diameter and mean length increase in successive orders of branching. An analysis based on the concept of minimum work suggests that ideally R d = R b 1 3 , whilst geometric considerations suggest that R 1 = R b 1 3 . Thus R d = R 1 These theoretical results are compared with those obtained from measuring one human and six dog bronchial tree casts. Values obtained from the human lung are in close agreement with the predicted values, whilst in the dog lungs the agreement, though less good, is still close. R b is determined antenatally, the reason for its particular value being unknown. Diameter and length of branches may be modelled postnatally by growth in a manner which ensures that R d = R 1 = R 1 3 .

PSYCHOLINGUISTICS DISCOVERS THE OPERANT: A REVIEW OF ROGER BROWN'S A FIRST LANGUAGE: THE EARLY STAGES1

Brown's book is selectively reviewed with the aim of noting points of similarity between Brown's psycholinguistic analysis of language acquisition and a functional analysis of verbal behavior. Brown divides early language acquisition into five stages, based on mean length of utterance in samples of child speech. His book concentrates on Stage I, when mean length of utterance first rises above 1.0, indicating that children are beginning to speak in multi‐morphemic utterances, and Stage II, when mean length of utterance in morphemes is about 2.25. Multi‐morphemic utterances in Stage I consist mainly of ordered sequences of uninflected nouns and verbs, the order being that of the simple declarative sentence (agent‐action‐indirect object‐direct object‐locative). The review attempts a theoretical analysis of the functional stimulus control of Stage I syntactic order, concluding that the control must originate partly in relations among events in the environment and partly in covert autoclitic verbal behavior. Increases in mean length of utterance in Stage II are mainly due to the appearance of several “grammatical morphemes” such as the progressive ‐ing inflection on verbs and the plural ‐s inflection on nouns. The review attempts a behavioral paraphrase, again in terms of tacts and autoclitics, of Brown's psycholinguistic analysis of grammatical morphemes, concluding that Stage II displays the further development, building on Stage I, of the combined control of verbal behavior by relations in the environment and covert self‐generated verbal stimuli. Similarities between Brown's psycholinguistic analysis and a functional analysis of language acquisition suggest that the two viewpoints are converging on a common concern with the stimulus control of verbal behavior.

Observations on the Planktonic Larvae of Polydora ligni Webster (Polychaeta: Spionidae) in the York River, Virginia

The occurrence of planktonic larvae of the polychaetePolydora ligni Webster was followed for a period of 12 weeks in 1970. Larvae first appeared on March 11 and weekly samples generally showed an increase in mean length throughout the sampling period. Larval length ranged from 0.19 mm to 1.15 mm. An initial settlement of metamorphosed larvae with a mean length of 1.25 mm occurred on test panels on April 14. The number of setigers was shown to vary directly with larval length. Larvae reared in the laboratory at 21 C required 19 to 28 days to develop fully, while larvae reared at 10 C required 60 to 69 days.

Overwinter Survival of Wild Fingerling Brook Trout in Lawrence Creek, Wisconsin

Overwinter survival of brook trout (Salvelinus fontinalis) from the 9-month-old fingerling stage to the 16-month-old yearling stage varied from 35 to 73% during 11 successive winters (1954–65). Mean survival through these first winters of life was 54%.Survival appeared to be independent of fingerling density most winters, and especially when September densities were less than 2200/km, as they were during 7 of 11 years. Overwinter survival tended to increase with an increase in mean length of fingerling stocks (r = 0.83++) and with an increase in winter water temperatures. Intraspecific predation did not appear to be a critical mortality factor. The survival advantage of increased fingerling size was probably related to increased physiological resistance to temperature-associated stresses rather than reduced vulnerability to predation.

THE pH TOLERANCE OF EMBRYOS AND LARVAE OF MERCENARIA MERCENARIA AND CRASSOSTREA VIRGINICA

1. The pH range for normal embryonic development of oysters was 6.75 to 8.75, and for clams, 7.00 to 8.75.2. More than 68% of the larvae of both clams and oysters survived at pH 6.25 to 8.75. The lower pH limit for survival of oyster larvae was 6.00 and for clam larvae, 6.25.3. The pH range for normal growth was 6.75 to 8.50 for clam larvae and 6.75 to 8.75 for oyster larvae. The rate of growth of both species dropped rapidly at pH levels below 6.75.4. The optimum pH for growth was 7.50 to 8.00 for clam larvae and 8.25 to 8.50 for oyster larvae.5. At pH 9.00 to 9.50 the percentage of eggs that developed normally, the percentage of larvae that survived, and the percentage increase in mean length of both species decreased rapidly.

The growth rate of the Long Rough Dab Hippoglossoides platessoides (Fabr.)

SUMMARYThe ages of 1426 female, and 135 male Long Rough Dabs have been determined from otolith readings. The females were found to live into their seventh year and reach 30.5 cm, compared with males that live to their fifth year and reach 19.0 cm in length. However, the mean increase in length per year for a given length, has been found to be the same. The growth of the females has been shown to fit the equation lt=26.437 (I—0.574t) and of the males lt=17.754 (I —0.585t). In the case of the females the observed and calculated values agree quite closely, but with the males there is a greater difference, and it is believed that the discrepancy is due to net selection. The suggestion is made that the calculated mean lengths for each age group are better estimates of those of the population than are the observed sample means. The two standard deviations limits can be estimated about the population means and the sample values are found to be within these limits.Comparison with previous studies shows that the Clyde fish are smaller and shorter-lived than more northern specimens, though broadly speaking the rate of growth for comparable ages is not so dissimilar.

Effect of Temperature on the Cell Length and Shape of Bacillus vulgatus

B. vulgatus cells, when growing at 37° and 20 °C. on agar-slants showed rapid initial temporary increase in mean length, while at 5° the increase was gradual and prolonged, with formation of very elongated cells. At 5°, where neither spore formation nor heat destruction of the cells interfered, as occurred at 20° and 37° respectively, maximum opportunity for modification of cell shape was given. Comparisons with data obtained on the growth rate of B. vulgatus at these temperatures indicate that increase in cell length occurred mainly during periods of low growth rate.