NEUBOSPORIDIUM. 85 



infecting" the nervous system of Teleostean fishes. Pfeiffer^ 

 in 1892 discovered a Myxosporidian in the cranial and spinal 

 nerves of the Grayling (Thyniallus vulgaris), the cysts 

 lying between the medullary sheath of the nerves and the 

 sheath of Schwann; Schuberg and Schroder^ in 1905 

 described a similar, but not identical Myxosporidian, which 

 they named Myxobolus neurobius, in the nerves of the 

 Brook Trout (Salmo fario) ; and in 1898 Doflein^ described 

 a Microsporidian, Glugea lophii (now known as Nosema 

 lophii), occurring in the ganglion cells of the central nervous 

 system of the Angler (Lophius piscatorius). 



The proportion of infected specimens of C. nigrescens is 

 considerable. Out of a total of twenty polypides examined, 

 Neurosporidium was found to occur in eight. 



Spherical or slightly oval spores of Neurosporidium 

 appear to set up a local degeneration in the nervous, deeper 

 layer of the external epithelium of Cephalodiscus, and in 

 the oval spaces so formed the parasites grow and sporulate, 

 and become surrounded by an ill-defined, somewhat irre- 

 gularly alveolar capsule (pi. 7, figs. 9, 12, 15, cjis.). This 

 capsule is not of the nature of an ordinary cyst, secreted by 

 the parasite peripherally, but would appear rather to be formed 

 by the surrounding tissue of the host, much in the same 

 way as is the enveloping membrane of the Sarcosporidia. 



The capsule is not in all cases clearly evident. Some of 

 the parasites, appearing as groups of spherical bodies when 

 examined under a Zeiss A or D objective, nearly fill the 

 spaces in the host tissue in which they lie, while others are 

 more or less closely surrounded by a capsule (pi. 7, fig. 12, 

 cps.), which itself is separated from the wall of the host tissue 

 by a space. The space (fig. 12, cav.) is bounded externally 

 by a thin layer of the same material (fig. 12, cj^s^) lining the 



' Pfeiffer, L., ' Uutersuchungen iiber den Krebs ; die Zellerkraukungen 

 und die Geschwulstbilduiigen durch Sporozoen,' 1893, p. 75. 



"^ Schuberg, A., and Schroder, 0., ' Archiv fiir Protistenkunde,' iv, 1, 1905, 

 pp. 50 et seq. 



3 Doflein, P.. 'Zool. Jalirb.,' Anat., xi, 1898, p. 332. 



