ENTOMOLOGICAL SOCIETY 



parasites" and " stationary parasites" including in the former 

 those organisms which visit their hosts only from time to time in 

 order to procure food, as Culex, Ctmex, Dermanyssus, etc. 

 The "stationary parasites" would include those organisms 

 which are with their hosts continuously for the whole or a por 

 tion of their life. In this class we can recognize two subdivisions : 

 the " periodical parasites" that is, those organisms which spend 

 only a period of their life as parasites, and the permanent para- 

 sites^i. e., those organisms which complete their entire life-cycle 

 as parasites. 



As examples of the former, we may cite the genera Mermis^nd 

 Gordius, which spend their larval stages in the body cavity of 

 insects, etc., or Nectonema, which, as H. B. Ward has recently 

 shown, is parasitic in fish for a portion of its life. Hypoderma, 

 Cuterebra, and Gastrophilus would furnish examples familiar to 

 entomologists. As examples of permanent parasites, we might 

 cite the Cestodes. 



Among the Nematodes, we find a most striking example of para 

 sitism which must be looked upon as intermediate between the 

 periodical and the permanent parasites. I refer to the genus 

 Rhabdoncma. R. nigrovcnosum, to take a specific example, is an 

 hermaphroditic (? or parthenogenetic) worm which, in alternate 

 generations (i, 3, 5, 7, etc.), is an obligatory parasite in the lungs 

 of amphibians (Rana, Bufo). In the 3d, 4th, 6th, etc., genera 

 tions the sexes are separate and the organisms are free-living 

 animals. 



Another division of parasites would be (A) the phyto-parasites 

 and (B) the zoo-parasites, and each of these may be subdivided, 

 according to whether they are parasitic upon plants or animals. 



Still another division of parasites is implied in Leuckart's defini 

 tion, /'. ., ectoparasites and endoparasites. 



In helminthology we frequently use the terms pseudo-parasites 

 and spurious parasites. Most authors do not make a distinction 

 between these two, but include the spurious parasites under the 

 head of pseudo-parasites. It seems to me, however, that there 

 is a difference between the two which it will be well to observe. 



Under pseudo-parasites I would include all those organisms 

 which as a rule do not live a parasitic life, but which happen by 

 chance to get into the body of an animal and live there for a short 

 period ; all pseudo-parasites would be facultative parasites, 

 although all facultative parasites are not pseudo-parasites. Mos 

 quito larvae, muscid Iarva3, or species of the genera Gordius and 

 Mermis are occasionally swallowed by chance ; upon coming 

 into the intestinal tract, they are capable of living a parasitic life 

 for a short time, but after a few days they are either killed and 

 digested or they are expelled from the body. Under the term 

 spurious parasites, on the other hand, I would include : (i) 



