ZOOLOGY. 337 



were found to be iueffectnal in advanced cases ; but if only slight degen- 

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

 teracted the efiects of previous i)rivatiou. As soon, however, as exten- 

 sive degeneration had taken jjlace no care was sufiQcient to recuperate 

 the patient. 



EHIZOPODS. 



A NEW "CLASS" OF RIIIZOPODS.* 



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

 forms of Ehizopods, which he subsequently described in a monograph 

 of the lla<liolaria as representatives of three distinct lamilies. In 1879 

 Hertwig differentiated these forms, with others subsequently made known, 

 as an order of Kadiolaria, under the name " Tripyle;e." A large number 

 of forms belonging to the group were obtained by the Challenger exi>e- 

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

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

 constant presence of large dark-brown pigmented granules, scattered 

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

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

 " pha?odium " (dark brown or dusky). " The phaeodella, large brown 

 granules of the '■ plupodium,' 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 ' plmeodium ' appears in 

 all ' Pha^odaria,' while it is wanting in all the typical Eadiolaria, gives 

 the Phseodaria a high degree of systematic imi^ortance." On account of 

 this " constant presence of the phseodium, 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 Eadiolaria, 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 E. Hertwig. Many Phteodaria have 

 only one such opening [MonopyJecv)^ others have two at the opposite 

 poles of the central-capsule {AmpMpiilew)^''' and still others more. The 

 siliceous skeleton is extra capsular. Although the principal forms of 

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

 ally readily distinguished from them. Haeckel has proposed teji "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 Kbizopoda. Nature, vol. xxi, pp. 449-451, March 11, 1880 

 S. Mis. 31 22 



