THE CYSTIC ENTOZOA. 495 



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

 to the parasite. My brother, in the paper already alluded to, 

 says, regarding the cyst " May we not suppose them to be 

 parts of the original ovum, within which 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 must 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 Csenurus, 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 Neuronaia 

 Monroii* (Plate VI., Fig. V ; Plate XI., Figs. 2, 7.) 



" The observations of Pacini J on the peculiar bodies which 

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

 attention to the l spheroidal bodies/ described by the second 

 Monro, as existing on the surfaces of the brain and nerves of 

 the gadidae. 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 Journal 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 the Structure and functions of the Nervous System 

 p. 59. 



t Pacini, Nuovo Giornale dei Letterate, March and April 1836, p. 

 109. J. Henle and Kolliker, -Ueber die Padnischen Korperchen an den 

 Nerven des Menschen und der Sdugethiere. 



