Handbook of medical entomology . nd Noe (1900),Noe(i9oi)andFiillebom(i9io).The larvae, as they exist inthe circulating blood, exhibit avery active wriggling movement,without material may exist in enormousniimbers, as many as five orsix hundred swarming in asingle drop of blood. This is the more surprising when we con-sider that they measure about 3oo[x x 8|x, that is, their width isequal to the diameter of the red blood corpuscle of their host andtheir length over thirty-seven times as great. Their organs are very immature and the structure obscure. Whenthey have quieted down
Handbook of medical entomology . nd Noe (1900),Noe(i9oi)andFiillebom(i9io).The larvae, as they exist inthe circulating blood, exhibit avery active wriggling movement,without material may exist in enormousniimbers, as many as five orsix hundred swarming in asingle drop of blood. This is the more surprising when we con-sider that they measure about 3oo[x x 8|x, that is, their width isequal to the diameter of the red blood corpuscle of their host andtheir length over thirty-seven times as great. Their organs are very immature and the structure obscure. Whenthey have quieted down somewhat in a preparation it may be seenthat at the head end there is a six-lipped and very delicate prepuce,enclosing a short fang which may be suddenly exserted andretracted. Completely enclosing the larva is a delicate sheath,which is considerably longer than the worm itself. To enter intofurther details of anatomy is beyond the scope of this discussionand readers interested are referred to the work of Manson and Elephantiasis in Man. From NewSydenham Societys Atlas. i8o Arthropods as Essential Hosts of Pathogenic Organisms One of the most surprising features of the habits of these larvaeis the periodicity which they exhibit in their occurrence in the peri-pheral blood. If a preparation be made during the day time theremay be no evidence whatever of filarial infestation, whereas a prep-aration from the same patient taken late in the evening or duringthe night may be hterally swarming with the parasites. Mansonquotes Mackenzie as having brought out the further interestingfact that should a filarial subject be made to sleep during the dayand remain awake at night, the periodicity is reversed; that is to say,the parasites come into the blood during the day and disappear fromit during the night. There have been numerous attempts to explainthis peculiar phenomenon of periodicity but in spite of objectionswhich have been raised, the most plausible remains that of Man
Size: 1426px × 1751px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsectp, bookyear1915
