James Murray

“ The instances of Life under Difficulties are all selected from the class of the Rotifers. The animals of this class, though so small, are comparatively very highly organised and sensitive, yet they share with the simplest animals, (the Protozoa) the power of surviving all kinds of climatic rigours, heat, cold, drought, etc..
Larger animals may protect themselves from heat and cold in various ways, or they may migrate to avoid them. Emperor Penguins and other animals which winter in polar regions, keep up their heat by means of thick layers of fat and warm coats of fur or feathers. ”

“ No such protection can serve our microscopic animals. A thin-skinned creature, measuring when contracted no more than one hundredth part of an inch in diameter, can hardly have a coating which will keep out cold and heat, and we can only suppose that they are able to live although they do become very hot and very cold when subjected to these conditions. ”

“ The capacity to resist heat is intimately related to that of withstanding drought. In a state of nature, some Bdelloids when dessicated, must also suffer very severe scorching from the tropical sun; yet mosses from tropical regions are found to be as productive of Bdelloid Rotifers as any others, and they readily revive when conveyed to temperate regions and steeped in cold water. ”

“ Those who have worked at the microscopic life of the Arctic Region know that it must survive extreme cold. somehow. The Arctic Region has a, genial summer climate of some months duration, with abundant water and a vegetation of higher plants. The winter might be passed by resting eggs, and a new generation produced each summer. ”

“ The Rotifers which are able to endure cold should interest us especially in our present circumstances, as they are at the moment under observation in the lakes around us at Cape Royds, and we have some personal experience of the cold which they have to undergo. ”

“ The leech-like creeping rotifers of the order Bdelloida supply the most remarkable instances of the capability to resist drought, as well as heat and cold. They are essentially aquatic animals, and can only remain active so long as they are surrounded by water. Yet many of them live in situations which are liable to become dry ”

“ Professor Richters revived Water Bears from Spitsbergen some years after they were collected, but it could not be known whether the adult animals would have survived the winter of their native land.
At Cape Royds there is no doubt that the adult animals survive through the winter. Some of the species lay eggs, but the eggs are not plentiful. One species (Adineta Grandis) produces living young, being an exception in this respect in the genus. The life both of parent and young may apparently be arrested at any stage. ”

“ Bdelloid Rotifers abound in the lakes of Cape Royds, and there are several species. The conditions to which they are submitted are extremely severe. They are frozen into the ice very early in the autumn, and must remain frozen solid for at least the greater part of the year. With the ice of the smaller lakes and the margins of the larger lakes they must take the lowest temperatures that occur in the district. We know by observation that they survive after experiencing a temperature of -30° Fahr.. ”

“ Whether an individual, after hibernating in this manner for many years, could again enter on a long hibernation, is not known, but groups of individuals have been revived again and again after shorter intervals, though in diminishing numbers, some dropping out after each resuscitation. ”