He estimated how many species of insects lived on each plant species in England, and then extrapolated that figure across the whole planet. âIf we say 400,000, we shall, perhaps, not be very wide of the truth,â he wrote. Today, scientists know the Westwood figure is far too low.
Symptoms: A chronic dry cough that's worse at night, disturbing sleep, and sometimes with wheezing and shortness of breath. Causes: An irritating night cough is often the first sign of asthma, especially in children, but you can develop it at any age. It's also a sign asthma is worsening or not being well controlled.
A chest X-ray may be needed to help evaluate your cough. A persistent dry cough can be caused by a number of different problems. Sometimes the cause isn't too worrisome -- for example, in a post-infectious cough -- but sometimes the cause is quite serious, as in cases of heart failure or cancer. In general, a persistent dry cough can originate from your lungs, your heart, your sinuses or your gastrointestinal system.