Charcoal-yeast extract agar is a new bacteriological medium that supports excellent growth of the Legionella pneumophila. It results from modifications made in an existing L. pneumophila medium, F-G agar. Yeast extract, instead of an acid hydrolysate of casein, serves as the protein source. Beef extractives and starch are not added. Activated charcoal (Norit A or Norit SG) is included at 0.20% (wt/vol). Comparison of charcoal-yeast extract and F-G agars showed that a greater number of colony-forming units of L. pneumophila was recovered from a standardized tissue inoculum on charcoal-yeast extract agar (4.35 x 106 colonyforning units) than on F-G agar (4.85 x 104 colony-forming units). Macroscopic colonies of L. pneumophila were visible on the new medium within 3 days, whereas 4 days of growth was required on F-G agar. McDade et al. initially isolated the Legionnaires disease bacterium, now named Legionella pneumophila, by using guinea pigs and embryonated chicken eggs (2, 9). For the purpose of growing L. pneumophila on artificial media, Weaver inoculated 17 different bacteriological agars with an L. pneumophila-infected yolk sac suspension. Mueller-Hinton agar supplemented with 1% hemoglobin and 1% IsoVitaleX (BBL

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The covariation of growth and maturation in male Atlantic salmon parr, Salmo salar, produces a relationship characterized by a size threshold below which individuals generally do not mature. The threshold of 70–72 mm fork length is evident both within and among populations. Parr maturation can reduce growth during the second year of life by an average of 4.0%. Among-year variation in growth rate affects the yearly incidence of maturation for males at age 1 + but has no detectable effect on the total proportion of male parr maturing in a population. Increases in the proportion of mature parr in the Matamek River, Quebec, can be explained by variation in growth alone; there is no evidence for genetic changes in this population.

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Pittsburgh pneumonia agent (PPA) was recently cultivated from infected egg yold on charcoal yeast extract agar. PPA has now been isolated both from infected egg yolk and human lung tissue on charcoal yeast extract agar and on a new medium, buffered charcoal yeast extract agar. PPA resembles Legionella pneumophila and other Legionella-like organisms in requirements for growth and composition of fatty acids. It differs in genetic relatedness, antigenic composition, and colonial morphology and has distinctive characteristics that allow it to be identified. The name Legionella pittsburgensis species nova is proposed for this organism.

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Atlantic salmon parr and brook trout were observed in stream tanks at the Matamek Research Station, Quebec. In the autumn, at 10 C Atlantic salmon parr began sheltering in rubble, and at 9 C the majority had disappeared into hiding. Brook trout also had this tendency to hide at cold temperatures, but not as strongly as the salmon. In slow water flows (<5 cm/s), Atlantic salmon parr tended to hide in the rubble substrate at any temperature, and aggression decreased. In both slow and faster water velocities during summer and autumn the commonest agonistic act by Atlantic salmon parr was "charge and chase." Brook trout in July showed "nip" as the commonest agonistic act, but in September and October "approach" and "charge and chase" were more common, possibly due to aggression associated with spawning. Shade was attractive to both species in shallow water, but given the choice of a shallow (30 cm) tank with a shade cover, and a deeper (50 cm) tank with no shade, the majority of brook trout and Atlantic salmon selected the deeper tank. In one experiment in a shallow-water tank, turbulent water surface was more attractive to Atlantic salmon parr than shade.Generally where juvenile Atlantic salmon, or parr (Salmo salar), and brook trout (Salvelinus fontinaIls) coexist, parr during the summer are more numerous in riffle areas than in pools, and brook trout are more common in the pools (Keenleyside 1962; Gibson 1966). This may partly be due to differences between the two species in habitat preference, or depth with size, but in some rivers, such as the Matamek River in Quebec, segregation is mainly brought about by behavioral interactions and by competition (Gibson 1973a). However, the distribution of Atlantic salmon parr and brook trout changes seasonally. They are difficult to catch in the Matamek River when the water is cold, as in May, but in mid-June they appear suddenly to become abundant. In early October they again disappear (Gibson 1973a). Allen (1940) remarked that Atlantic salmon parr in the River Eden in England disappeared from the riffles when the water temperature reached 7 C at the end of October, and did not reappear until the water temperature again reached 7 C the following March. Saunders and Gee (1964) found in a • Contribution 3982 from the Woods Hole Oceanographic Institution. Contribution 30 from the Matamek Research Station, Quebec. 2 Present address: MacLaren Marex, Inc., St. John's, Newfoundland A1A 2Y4.New Brunswick stream that in December,

The effects of winter and summer river discharge on the survival of eggs and underyearlings of Atlantic salmon (Salmo salar) were examined in six rivers of Newfoundland and New Burnswick where stock–recruitment relationships were available. There were positive relationships between either winter discharge or temperature and survival of underyearling salmon for five rivers. For all rivers combined, survival and winter discharge were related (P < 0.05). The hypothesis that summer discharge was unrelated to survival could not be rejected. However, there was evidence that summer discharge enhances survival in the Miramichi and Northwest Miramichi rivers of New Brunswick.