THE CYSTIC EXTOZOA. 40o 



infested being, and Dr. Knox* again, that it belongs essentially 

 to the parasite. ]\Iy brother, in the paper already alludetl to, 

 says, regarding the cyst — " ^lay we not suppose them to be 

 parts of the original ovum, within whieh the animal was formed, 

 and within which it passes its term of existence." From ob- 

 servations made on the development of the Acephalocystic 

 entozoa, it may be safely stated, I think, that the above state- 

 ment is correct, for Acephalocystis nmst be considered as an 

 enlarged ovum ; but Sphairidion perhaps is the best example 

 of this peculiar mode of formation, the "inserted pedicle" being 

 analogous to the confined Trichina or Gymnorhynchus — for 

 we must look upon the inserted pedicle as the active animal. 

 In Cajnurus, also, the pedicles are contained within the ex- 

 ternal membrane of the sac. 



I shall finish these observations on the Cystic Entozoa, 

 with the following account by my brother John, of Ncuronaia 

 MonroiLi (Plate VI, Fig. 7 ; Flate XL, Figs. 2, 7.) 



" The observations of Pacini \ on the peculiar bodies which 

 are appended to the digital nerves, induced me to direct my 

 attention to the ' spheroidal bodies,' described by the second 

 ^lonro, as existing on the surfaces of the brain and nerves of 

 the gadidai. I accordingly examined the * spheroidal bodies ' 

 in the haddock, and found that they were entozoa, referrible 

 to the family Distoma, and enclosed in cysts. I described 

 these curious parasites at a meeting of the Anatomical and 

 Pathological Society, and a short abstract was published 

 in the Monthly Jounud of Medical Science. Till lately, I 

 had supposed that I was the first to observe the true nature 



• Knox, Edinburgh Medical and Surgical Journal. 



t Monro, Observations on Vu Structure ami functions of Uic Xcrroits Sysictn, 

 p. 59. 



* Pacini, Nuovo Giomale dei LcUeratc, Mun-li antl \\\\\\ 1S36, ]>. 

 109. .T. Hi-nle and Ktilliker, Utber die racinischcn KDrpcrchai an dm 

 Xerirn <li\s Mcnschcn uiid dcr Sduijcthierc. 



