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A small population of birches was studied with a view to measuring the rangeof morphological variation in Betula pendula Roth, and B. pubescens Ehrh. The general morphological features of crown and bark of trees in the area indicated that both species were present. A more detailed study was made of leaf and fruit characters, accepted by other investigators as being useful in discriminating between the species. It was shown that such characters varied continuously throughout the population and no tree was wholly pubescens- like or pendula-like in all characters.The implications of these results are discussed in relation to the situation in Glen Gairn and to the general taxonomic situation of the British birches.

THE MAINTENANCE of a constant body temperature is dependent upon two distinct bodily functions, heat production and heat loss. The balance between these two mechanisms maintains the body at optimum temperature. An undue fall in body temperature is brought about by a reduction of metabolic heat, as well as the actuation of such processes as sweating and dilatation of cutaneous vessels. Heat production results from an increase in metabolism, as well as such mechanisms as shivering and constriction of cutaneous vessels. That these two mechanisms are structurally distinct has been shown by studies in which one has been eliminated, leaving the other intact (Keller,1 Bazett,2 Alpers,3 Teague and Ranson,4 and Ranson and associates5).Tscheschichin6 was the first to insist that there was a definite heat center somewhere above the medulla. In 1885 Aronsohn and Sachs7 first called attention to a possible heat center

OWING to the increasing knowledge of bulbar physiology and the improved methods of treatment of bulbar poliomyelitis, many more patients affected with severe bulbar poliomyelitis are surviving the acute illness and are returning home apparently recovered except for scattered weaknesses of bulbar musculature. However, many of these patients, although apparently recovered and comfortable in the protected environment of the hospital, encounter considerable difficulty when exposed to even moderate stress of everyday life. The slightest physical exertion, the routine environmental infections, or even mild daily excitements and problems precipitate many untoward physical discomforts, which indicate an instability of function of the nervous system. Even more serious is the occasional case in which the patient suddenly succumbs weeks, or even months, after an apparently complete recovery and no specific cause can be discovered for this tragic outcome.Since these patients are comfortable in the protected hospital environment and experience symptoms when exposed

THE COMBINATION of symptoms referable to the pyramidal system, anterior horn cells, and lower brain stem constitutes the syndrome of amyotrophic lateral sclerosis. The literature contains many case reports of this syndrome in which varied etiologic factors have been determined. Wechsler and associates1 analyzed 81 cases of amyotrophic lateral sclerosis and listed dietary deficiency and inflammatory, vascular, and toxic processes as etiologic factors. This clinical symptom complex has been noted following gastrectomy2 and polyarthritis,3 and in triorthocresyl phosphate poisoning.4 It has recently been considered an atopic-stress disorder, and some improvement has been obtained by the use of adrenocortical extracts.5 Cord tumors, syphilis, and arachnoiditis may also produce this syndrome. It becomes obvious that the physician in his evaluation of such a symptom complex must seek the clue to the etiology by a careful and detailed search into the patient's occupation, contacts, illnesses, and injuries, since

IN BULBAR poliomyelitis the hypothalamus shows evidence of microscopic damage in 85% of the cases. Clinical evidence of severe hypothalamic involvement in this disease is manifested by diverse symptomatology, including aberrations in temperature regulation, water metabolism, carbohydrate metabolism, cardiovascular control, and gastrointestinal activity. Since a large number of patients with bulbar poliomyelitis do have definite damage to the hypothalamic nuclei, one would expect many of the recovered patients to show some clinical evidence of such involvement. Unfortunately, there has been no single test or combination of tests which would enable one to adequately evaluate the status of this area of the nervous system.Adjustment to our constantly changing environment is effectively carried out by the hypothalamus under normal circumstances. Although invested with considerable reserve through its complicated connections, the hypothalamus when damaged is unable to control bodily responses adequately. Because of the importance of this regulatory center to the body

DESPITE the relatively few articles referring to the intramuscular use of succinylcholine,1-3 this technique has been employed with increasing frequency in the last few years. Investigation of the neuromuscular effect of 4.0 mg. of intramuscular succinylcholine per kilogram of body weight in adults4 revealed that this dose produced apnea of 14.7 ± 1.5 minutes' duration in 155 ± 15.6 seconds. The tidal volume of respiration returned to control in 30.3 ± 2.1 minutes.It had been reported earlier that the duration of action of intravenously injected succinylcholine was inversely proportional to the plasma cholinesterase level in patients who had severe cirrhosis of the liver.5 It is also known that the neuromuscular effects of intravenous succinylcholine are excessively prolonged, out of proportion to the decrease of the plasma cholinesterase level, in seemingly normal subjects whose plasma cholinesterase is "atypical."6 The relationship between the enzymatic hydrolysis rate of

THE identification of unknown compounds separated by gas chromatography is often effected by comparison of their retention values with those of known compounds together with infra-red spectro-photometry or mass spectrometry. For this purpose graphs are prepared of log r against boiling point or log r on one stationary phase against log r on another stationary phase, where r is the retention time, relative retention time or the retention volume. Both non-polar and polar stationary phases are used to indicate the nature of the unknown substance. Wehrli and Kovats1have shown a relation between the structure of the substance and its retention values on two such phases. Stationary phase liquids which can take part in electron donor–electron acceptor interactions have also been used by Langer et al.2and Janak and Hrivnac3to separate closely similar pairs of compounds. I have also found4three different stationary phases to be useful in identifying components of a brown coal tar.