Icelandic ewes, living under natural photoperiod conditions, were treated with daily melatonin (2.5 and 10 mg day-1) for 75 days from the autumn equinox. Ewes were also exposed to a ram from the autumn equinox until the end of June, for 30 days from the end of the anoestrous period (30 October), and from 11 December for 30 days during the oestrous season. Blood samples were collected three time...

Seasonal adaptation is a ubiquitous behavior seen in many species on both global hemispheres and is conveyed by changing photoperiods. In humans this seasonal adaptation is less apparent, in part because changes in daylength are masked by the use of electrical lighting at night. On the other hand, cataracts which reduce light transmission, may compound seasonal changes related to the reduced da...

Patterns of seasonal activity and density of host-seeking western blacklegged ticks, Ixodes pacificus, were investigated in central and southern California. Weekly to monthly drag sampling was undertaken at two sites in Santa Barbara County and one site in Los Angeles County over multiple years. Adult I. pacificus became active in the winter (late November) and were rare or absent by late April...

A seasonal difference in the temperature-pulse rate curve of the isolated frog's heart was described by Barcroft & Izquierdo (1931). In the summer they found an almost linear relation between temperature and frequency of pulsation from 5 to 20 C, while in the winter the relation was exponential over the same temperature range. Carter (1933) investigated the effects of various endocrine and rela...