Microscopical Society. 1363 



young Filariae are numerous opaque oval bodies with an irregular out- 

 line and coarse granular aspect, and which appears to constitute a 

 part of the grumous matter forming the matrix of the young, but there 

 is nothing that can be considered in the light of ova, nor are the 

 young ever observed to be attached in any way to the parent. 



The life of the Filaria Medinensis, as a parasite, admits of being di- 

 vided into two periods or portions ; during the one of which it is 

 latent or exhibits no sign of its presence in the human frame, and in 

 the other it has manifested its existence by several external symptoms, 

 and makes its egress either spontaneously or with the assistance of 

 art. The former of these periods may be taken as extending over, 

 from twelve to eighteen months. The worm, during this period 

 does not appear to exert any injurious influence on the tissues among 

 which it is lodged. When arrived at maturity, however, it comes to 

 the surface, and is either brought away or comes away piecemeal ; of 

 course this affording an opportunity for the dispersion of the vivacious 

 young with which its interior is crammed. 



Taking all these facts into consideration, it was suggested that the 

 Filaria Medinensis in its parasitic form presented an instance among 

 the Nematoid Entozoa, of an intermediate or transition generation, 

 such as have been shown to exist in most of the lower classes of ani- 

 mals by several naturalists, and especially by a Danish naturalist, 

 Steenstrup, whose work on the subject of alternating generations, has 

 recently been published under the auspices of the Ray Society. In 

 this work the intermediate generation or form is provisionally termed 

 a " nurse " or •' nursing generation," and it may be thus briefly cha- 

 racterized : — 



1st. That it is unisexual and female, inasmuch as it always contains 

 young. 



2nd. That the female apparatus is modified in all " nursery genera- 

 tions " by the abortion, or in the deficiency of certain portions of the 

 generative tube — to wit, the ovary and oviduct. Nothing being re- 

 tained but the uterus, or what is analagous to it. The " nurse " being 

 as it were an " individualized uterus." 



3rd. That it is always proligerous, never oviparous, and besides 

 these points it may be remarked that in most cases where this mode 

 of generation obtains the only way of escape for the young is by the 

 rupture of the body of the parent. 



It will be readily observed that the Guinea Worm agrees in all these 

 conditions with the definition of a " nurse " or "nursing generation," 

 and the supposition of its being in fact, a creature of that kind, is sup- 



