Vasa deferentia from age-matched spontaneously hypertensive rats (SHR) compared with three strains of control rats were found to be hyperresponsive to low concentrations, 10 and 20 mM, of KCl (K+) but not to noradrenaline (NA); the SHR tissue also demonstrated a lower ED50 to K+. Significant differences in maximum tension between SHR and the control animals in response to K+ were not seen although maximum tension developed to K+ was always greater than that developed to NA in either SHR or a control group. The loss of contractile response to K+ in the absence of extracellular calcium was more rapid in the SHR than in the control animals but no such difference was noted for the loss of response to NA. Differences in the Ca2+ dependence of KCl responses were found for 15- to 17-week-old SHR but not for 5- to 7-week-old SHR while differences in the Ca2+ dependence of the NA response were noted in the younger age group of SHR but were less evident compared with the K+ response in the older age group of rat. The 15- to 17-week-old SHR, but not 5- to 7- or 9- to 11-week groups, also demonstrated a hypersensitivity to Ba2+ whereas both SHR and normotensive control tissues demonstrated an extracellular Ca2+-independent and D 600 insensitive contractile response to lanthanum (La3+). The contractile response of the vas deferens to La3+ could, in part, be related to an effect of raised H+ but a pH-independent action of La3+ was also evident from studies with Tris-buffered solutions. Although the action of La3+ was similar in both SHR and control rats the SHR tissue was shown to be more sensitive to H+. The results demonstrate an altered threshold sensitivity and altered responsiveness of nonvascular smooth muscle in the SHR which parallels, in some respects, previous studies indicating altered vascular smooth muscle responsiveness to a variety of physiological and nonphysiological stimuli in the SHR. Furthermore, these studies may indicate that a generalized genetic alteration in the sensitivity of the smooth muscle cell to chemical stimulation and Ca2+ utilization may persist in the SHR. Whether such differences relate to the elevated blood pressure and etiology of hypertension is not yet clear.

cleaned at the works agreed almost exactly with the laboratory filtration results, the former curve being, of course, inverted. The inference seems to be that by the periodical examination of reservoir water the life of the sand-filters can be judged.with tolerable accuracy. ALGAL-INFECTED WATERS. The next section (No. 12) was devoted to the treatment of algal-infected waters with copper sulphate. It was pointed out that the dose required to kill the different organisms varied within very wide limits. The maximum dose is hardly permissible, and with smaller doses there is always the chance of the way being paved for the active development of more resistant forms. Utilising this line of thought, the lecturer, for purposes of illustration, conjectured the possibility of, in a partial sense, a series of doses of copper sulphate leading to the growth of widely different organisms. To give point to his meaning, Dr. Houston showed a most beautiful series of slides in the following order : Uroglena ; Asterionella, Anabcena, and Synura; Spirogyra and Oscillaria ; Fragillaria and Volvox ; Dinobryon ; Synedra ; and, finally, Ceratium. As Dr. Houston remarked, when you interfere with the balance of nature you can never be quite sure of the ultimate consequences. Subject to the treatment being carried out by experts, the lecturer, however, was not opposed to the judicious use of copper sulphate as an algicide. Apart from sentiment, it may be a sound financial proposition to anticipate algal troubles by an inhibitory dose of copper sulphate, as this may mean prolonging the life of the filter beds very considerably. Apparently copper sulphate is a better algicidal ' ' than bactericidal agent, the converse holding true with the hypochlorites. In Section 13 the lecturer dealt with the taste of algalinfected water. The descriptions given to these tastes and odours by scientists (e.g., geranium, mossy, cucumber, grassy, violet, nasturtium, &c.) carry small conviction to the consumer, who is apt to use more forcible expressionse.g., like castor oil or rotten fish. Asterionella, Cyclotella, Anaboena, Oscillaria, Dinobryon, Volvox, Uroglena, and Synura, are but a few of the growths which have been credited with the production of evil tastes. A beautiful slide of Tabellaria was shown, and it was stated that the geranium-like taste produced by this growth could be successfully overcome by a small dose of postassium permanganate (5lbs. per million gallons). Hypochlorites, in comparison, are of little use as "taste removers." FILTRATION-WATER AND DISEASE. Having dealt in previous sections with the River Thames from the physical, chemical, and bacteriological points of view and with the changes which occur in it consequent upon storage, the lecturer proceeded (in Section 14) to consider the effect of the last stage in the purification process (namely, filtration) on the quality of water finally delivered to consumers.

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