FOUND IN THE C )EL()M OF SAGITTA. 



323 



central position in the body, the latter assumes the form of an enveloping 

 basketwork that we have seen in the full-grown individuals. Bodies 

 similar to the non-plasmic spherules have been known from some astomatous 

 infusorians. As such may be mentioned the granules observed by Kofoid 1 ' 

 in Protopl/rya ovicola Kof. and interpreted by him as a highly differentiated 

 metaplasmic substance. So likewise the peculiar spherules mentioned by 

 Metcalf 2 ' from both the ectoplasm and entoplasm of Opalina . I should 

 think it highly probable that all the various cytoplasmic inclusions here 

 referred to are in fact chemically nearly related substances and represent a 

 nutritive substance stored up in the body. 



Xow as to the systematic position of the new genus and species. An 

 attempt was made by Cépède 3 ' to exclude Opalina, alleged to be without 

 micronucleus and the contractile vacuole, froms the Astomata, which group 

 was thus made to include only the heterokaryote forms in possession of the 

 contractile vacuole. This procedure CÉpède's seems to me scarcely tenable 

 in view of our present extended knowledge of the nature of micronucleus 

 and of vacuoles, both contractile and non-contractile. Of the occurrence 

 of these organellae in Opalina, Opalinopsis, and Chromidina, the 

 reader is referred to the recent works of Metcalf on Opalina and of 

 Dobell on Opalinopsis scpiolac and Chromidina clcgans, and to the 

 view expressed by Hickson in Lankester's Treatise on Zoology 

 (Protozoa, Part I) with regard to the presence of micronuclei in 

 Opalina. The Astomata in the restricted sense was divided by Cépède 

 into eleven families, making use of distinctive characters which, to my 

 mind, appear to be scarcely of more than generic value. For the present 

 at least, I should rather abide by the older scheme of Léger and 

 Duboscq 4) who divided the Astomata Scheviakoff simply into two 



1) Kofoid, C.A. — On the structure of Protoplirya ovicola, a ciliate infusorian from the brood-sac 

 of Littorimi rudis Don. The Mark Anniversary Volume, art. V, 1903. 



2) Metcalf M.M. — Studies on Opalina (preliminary notice). Zool. Anz., Bd. XXXII, 1907. 



3) CÉpkde, C. — Recherches sur les infusoires astomes. Arch. d. ZjoI. Exp., tome III, 5e ser., 

 1910. 



4) Léger, L., and Duboscq. O. — Les Astomata representent-ils un gro.ip naturel ? Notes sur les 

 infusoires endoparasites. Arch. Zool. Exp., 4e ser., 1904. 



