The sea anemone Calliactis tricolor and its association with the Hermit crab Dardanus venosus

The association of certain sea anemones and hermit crabs is established in different ways according to the species involved. The present study shows that the behaviour patterns of the two partners in associations between Calliactis tricolor (Lesueur) and Dardanus venosus (H. M. Edwards) in the Caribbean are similar to those seen in the Mediterranean C. parasitica and D. arrosor .
Although about half the crabs display an active behaviour pattern in laboratory trials, the anemone frequently settles on shells unaided and most C. tricolor respond to molluscan shells by clinging with their tentacles until the pedal disc can be attached. As a rule it is necessary for the anemone to relax and to cling to the shell if the crab is to be successful in transferring the anemone to its shell.
The behaviour patterns of D. venosus include a distinctive tapping of the edge of the base of C. tricolor after which the anemone is pulled or lifted off and transferred to the shell. An experimenter can also cause the anemone to relax and to detach itself by tapping the edge of the base with plastic rods after the manner of the crab.
The mechanisms by which the tentacles of Calliactis cling to, and by which the base settles upon, shells still remain to be elucidated. The participation of nematocysts in these processes could not be demonstrated in this study.
C. tricolor is found on some other pagurid and non-pagurid crabs in various localities. These associations need to be investigated fully in order that the behaviour patterns of C. tricolor may be correctly interpreted and compared with those of other species of Calliactis .     

The 131I Ortho-iodohippurate Photoscan in Human Renal Allografts

Nine examples, in seven patients, from a large cadaver renal allograft program, illustrate the value of radio-hippuran photoscans in differentiating causes of post-implant oliguria. Hippuran scans are shown to be more valuable than chlormerodrin scans when renal function is acutely depressed. Hippuran scans aided in the decision to remove kidneys in four cases of severe oliguria and to retain kidneys in two others. In two further examples, extravasation of urine was detected by scanning after radio-hippuran injection when other tests had failed to do so.The technique of radio-hippuran scanning has a place in the differentiation of acute and subacute renal dysfunction and has proved particularly valuable in the early oliguric complications of a cadaver renal transplant program.     

Natural History of Isolated Patent Ductus Arteriosus and the Effect of Surgical Correction: Twenty Years' Experience at The Hospital for Sick Children,Toronto

Seven hundred and forty-four cases of patent ductus arteriosus were diagnosed at The Hospital for Sick Children, Toronto, in the 20-year period from 1947 to 1966. Of these 705 have been treated surgically. It is concluded that operation is best performed between 6 and 12 months of age. Isolated ductus arteriosus is rarely a cause of congestive heart failure, and is more likely to be so in the presence of the rubella syndrome. Failure associated with the anomaly in the neonatal period can usually be successfully managed by medical treatment. Spontaneous closure after one month of age is not to be expected. Surgical treatment at the appropriate time prevents the subsequent development of Eisenmenger''s complex.     

ELECTRON MICROSCOPIC OBSERVATIONS OF RAT AND MOUSE CEREBELLUM IN TISSUE CULTURE

Closely ordered stages of myelin formation in cultures of newborn rat and mouse cerebellum, selected by direct light microscopy, were studied with the electron microscope. Electron micrographs of these cultures reveal the presence of neurons, axons, neuroglia, microglia, and ependymal cells. The appearance of the neuron is identical to that previously described in vivo. The neuroglial cell has long, branching processes, and its cytoplasm is characterized by packets of long, narrow fibrils. During myelin formation, a glial cell process surrounds the axon. This process may form an internal mesaxon and may spiral for several turns around the axon. Other glial cell processes may interdigitate with or overlay the innermost process to contribute to the multilamellated structure. The glial processes flatten and the cytoplasmic surfaces of the cell membrane come into contact to form the lamellae of the myelin sheath. These adhesions may be temporarily incomplete as evidenced by sequestered islands of glial cytoplasm among the myelin lamellae. Ultimately, a compact, apparently spiral, myelin sheath is formed. These findings are discussed in relation to in vivo central myelin formation.     

Cerebrovascular Occlusive Disease—Experience with Panarteriography in 300 Consecutive Cases

Three hundred patients with cerebrovascular occlusive disease have had cerebral angiographic examination at the Veterans Administration Hospital, San Francisco, in the last five years. The present technique consists of preliminary visualization of the aortic arch and the major extracranial branches, followed by selective study of the subclavian and carotid arteries as necessary for evaluation of the intracranial circulation.Nine major complications occurred (an over-all incidence of 3 per cent). Two patients died after angiography and seven had major neurologic deficits persisting for more than 24 hours. Three of these patients had permanent damage, but four recovered completely.One-third of the patients had extracranial disease and one-third had intracranial disease. No significant lesion was found in the remainder. In the 212 patients with lesions, multiple lesions were common, the average number being three. Six patients had brain tumors and five had aneurysms.The mechanism of the stroke could be ascertained readily in most of the patients, but the extent of the disease and the resulting symptoms varied considerably. Several patients with occlusion of most of the cerebral vessels had minimal symptoms, while others had catastrophic symptoms but only minimal findings at arteriography.