Dr. Kassai Tibor szerk.: Parasitologia Hungarica 2. (Budapest, 1969)

worthwhile, with special regard to the following pointB of inquiry: is there any systematic relationship between the species occurring together; are they in any way interdependent on one another; do certain species favour coexistence; are there species which seldom if ever occur coexist with others; finally, is there any apparent reason, ecological or otherwise, for the common occurrence of species or is it merely a spontaneous or chance phenomenon? Materials and Methods Since methods for collection of fleas or their hosts are well known only a summary of methods used in this study will be given.Mouse and shrew species were collected by live and lethal traps, dormice and hedgehogs by hand, moles and mole-rats by subterranean lethal traps, gophers either by hand (flooding with water) or by shooting, bats by nets or by hand (single specimens), all other mammals (squirrels, foxes, badgers, wildcats, martens) by shooting. Immediately after capture, the host specimens were placed in a sealed cotton sack and later in chloroform vessels; thus all fleas present on the host at the moment of capture were securely collected after narcotization. Great weight was laid on gathering the fleas separately by host specimen, except for cases when individuals of the same host species were caught in traps on further than a few steps from one another, since in all probability their fleas occurred on members of the same family living in a common subterranean burrow. The fundamental requirement for establishing conditions of coexistence of flea species per individual host is a recording system (Pig. l) which allows one to discover, at any time, the numbers and species of fleas originating from a given host specimen. The serial inventory number must also be entered for the host in question (Pig. l) since without this, had the flea specimens been preserved either in alcohol or mounted on a