ZOOLOGY. 337 



were found to be ineffectual in advanced cases ; but if only sliglit degen- 

 eration of the tissues had taken place, food judiciously supplied coun- 

 teracted the effects of previous privation. As soon, however, as exten- 

 sive degeneration had taken place no care was sufficient to recuperate 



the patient. 



EHIZOPODS. 



A NEW "class" of EHIZOPODS.* 



As long ago as 1859, Professor Haeckel had known several peculiar 

 forms of Rhizopods, which he subsequently described in a monograph 

 of the Radiolaria as representatives of three distinct families. In 1879 

 Hertwigdiflferentiated these forms, with others subsequently made known, 

 as an order of Radiolaria, under the name " TripylejT^." A large number 

 of forms belonging to the group were obtained by the Challenger expe- 

 dition, and have been subjected to a critical study by Haeckel, and, as 

 Murray first showed, " a striking character of all these Rhizopods is the 

 constant presence of large dark-brown pigmented granules, scattere<^l 

 irregularly round the central-capsule, and covering the greater part of 

 its outer surface." This extra capsular mass is called by Haeckel the 

 " ph^odium " (dark brown or dusky). " The phaiodella, large brown 

 granules of the ' phaiodium,' are not, as Murray supposed, true pigment 

 cells, as a true cell nucleus can not be observed in them ; and the nature 

 of the peculiar pigment of these pseudo-cells is not precisely known ; 

 but the quantity and constancy with which the ' phaiodium ' appears in 

 all ' Phaiodaria,' while it is wanting in all the typical Radiolaria, gives 

 the Phaiodaria a high degree of systematic importance." On account of 

 this " constant presence of the phaiodium, and the peculiarly constructed 

 membrane of the central-capsule," the type thereby differentiated is iso- 

 lated and a distinct " class" constituted for it. The species generally 

 attain considerable size, in comparison with other Radiolaria, and are 

 even visible to the naked eye. Many are a half millimeter or more in 

 diameter. " The conspicuous central capsule is usually round or sphe- 

 roidal: it is, however, often egg-shaped or somewhat oval. In many 

 cases it is monaxial ; in others dipleuric. Its membrane is very firm 

 and always double, the outer layer very thick, the inner thin. The 

 opening through which the pseudopodia appear has the very peculiar 

 structure accurately described by R. Hertwig. Many Phjemlaria have 

 only one such opening {MonopylecK), others have two at the opposite 

 poles of the central-capsule {AmphipijUcc),^ and still others more. The 

 siliceous skeleton is extra capsular. Although the principal forms of 

 this group have analogues among the typical Radiolara, they are usu- 

 ally readily distinguished from them. Haeckel has proposed ten " fam- 

 ilies," and these have been segregated by him under four "orders," 

 distinguished severally by characteristics of the skeleton, or the absence 

 of a skeleton. He has found among the forms examined by him what 



he calls more than 2,000 new species ! 



* A new class of Ehizopoda. Nature, vol. xxi, pp. 449-451, March 11, 1880 

 S. Mis. 31 22 



