THE INSURGENCE OF LIFE 139 



spinning larvse are campodeiform in type, that is, not so 

 worm-like as ordinary caddis-worms, and they differ also 

 in being very sedentary and practically carnivorous. The 

 author writes (in 1911) : ' It seems strange that until now 

 we have hardly had any idea at all as to the spinning powers 

 of these animals ; as the spider spins its web above ground, 

 and Ues in wait for the winged insects and the flying plank- 

 ton of the air, so the campodeoid larva constructs its net, 

 lurking for the small animals and floating plankton of 

 lakes and water-courses.' 



Strange Habitats. — In hunting for earthworms one does 

 not naturally look up a tree, but Dr. Eobert Stager has 

 shown that it is a useful plan to search in unlikely places. 

 In exploring on the Alps he investigated the mossy cushions 

 which often flourish on the stem and branches of the 

 sycamore and bear ferns and various flowering plants. In 

 that strange habitat he found four different species of 

 earthworm. Others occurred in the familiar cushions 

 formed on ahnost bare rock by plants like Dryas octopetala, 

 Silene acaulis, and Gypsophila repens. Again we have illustra- 

 tion of the way life insinuates itseK into every vacant niche. 



Another strange habitat is that of an ' unsalamander-like 

 salamander ' {Autodax liigubris) which lives up trees 

 {Quercus agrifolia). W. E. Ritter found them in holes at 

 a height of 30 feet, sometimes as many as a dozen in one 

 hole, representing perhaps a family. Most of the cavities 

 occupied had very narrow openings. The eggs are hung 

 in clusters from an overhanging surface, each egg on a little 

 string of its own, and both sexes look after them. Most 

 Amphibians are gentle creatures, but these Salamanders 

 are very ready to show fight in defence of their eggs or 

 themselves, and they have very large teeth. 



