On the development of Filaria sanguinis hominis, and on the mosquito considered as a nurse / by Patrick Manson.

  • Patrick Manson
Date:
[1878]
Catalogue details

Licence: Public Domain Mark

Credit: On the development of Filaria sanguinis hominis, and on the mosquito considered as a nurse / by Patrick Manson. Source: Wellcome Collection.

    6/16 (page 304)
    On the Development of Filaria sanguinis hominis, and on the Mosquito considered as a Nurse *. By Pateick Manson, M.D. (Communicated by Dr. Oobbold, E.B.S., E.L.S.) Development cannot progress far in the Host containing the Parent Worm.—Portunately it is an almost universal law, in the history of the more dangerous kinds of Entozoa, that the egg or embryo must escape from the host inhabited by the parent worm before much progress can be made in development. Were it possible for animals so prolific as Filaria immitis of the dog, or Filaria sanguinis of man, to be born and matured and to reproduce their kind again in an individual host, the latter would certainly be overwhelmed by the first swarm of embryos escaping into the blood, as soon as they had made any progress in growth. If, for example, the brood of embryo Hilaries, at any one time free in the blood of a dog moderately well charged with them, were to begin growing before they had each attained a hundredth part of the size of themature Filaria, their aggregate volume would occupy a bulk many times greater than the dog itself. I have calculated that in the blood of certain dogs and men there exists at any given moment more than two millions of embryos. Now the individuals of such a swarm could never attain any thing ap¬ proaching the size of the mature worm without certainly involving the death of the host. The death of the host would imply the death of the parasite before a second generation of Hilaries could be born, and this, of course, entails the extermination of the species; for in such an arrangement reproduction would be equivalent to the death of both parent and offspring, an anomaly impossible in nature. The Embryo must escape from the original Host.-— It follows therefore that the embryo, in order to continue its development and keep its species from extermination, must escape from the first host in some way. After accomplishing this it either lives an independent existence for a time, during which it is provided with organs for growth not possessed by it hitherto ; or it is swallowed by another animal which treats it as a nursling for such time as is necessary to fit it with an alimentary system. The former arrangement obtains in the Filarice inhabiting the * [Throughout this memoir Dr. Manson employs the term “ nurse '’ in the same sense as that in which helminthologists use the term “intermediate host.” —T. S. COBBOLD.]