302 w. aucher. 



homogeneous protoplasm-zone, surrounding the whole inner 

 space like a thick membrane." To this Hertwig and Lesser 

 are opposed, nor does there really appear any such distinct 

 separating layer, however thin, and the seeming boundary is 

 due only to a somewhat sudden alteration of the size of the 

 vacuoles and the varied thickness and degree of granula- 

 tion of their walls. The vacuoles of the outer region in 

 small individuals form but a single stratum, in larger several 

 occur superimposed, and more or less radiately arranged. In 

 the endosarc, the vacuoles are quite irregular. In very 

 young individuals there is no differentiation of endosarc and 

 ectosarc perceptible, and this becomes by degrees more and 

 more pronounced in larger examples. But Greeff went 

 further and explained the endosarc as " central capsule," 

 manifestly an erroneous conclusion. The central capsule of 

 the Radiolaria proper is composed of firm doubly contoured 

 chitinous membrane, but here there is no coat of any sort 

 around the middle region. 



Moreover the central capsule is an organ of reproduction, 

 in so far that by subdivision of its contents zoospores are 

 produced serving to reproduction. It does not play a part in 

 assimilation, which is exclusively performed by the extra- 

 capsular sarcode. On the other hand the endosarc of Acti- 

 nosphserium is the peculiar seat of the digestive function, 

 foreign bodies rarely being found in the ectosarc region, 

 except in transitu inwards. 



As is well known, sudden external forces cause retraction 

 of the pseudopodia and partial obliteration of the external 

 vacuoles ; after rest the organism slowly reassumes its 

 ordinary appearance. 



The marginal contractile vacuoles differ in nothing (are 

 scarcely even as a rule larger) than those of of Actinophrys 

 sol. 



The nuclei are very numerous, possibly considerably over 

 100 in large examples. Carter supposes he must have ob- 

 served as many as 400 in one individual : they occur only 

 in the endosarc, and, indeed, mainly confined to its outer 

 part. They form globular or subelliptic bodies, with rounded 

 nucleolus, and, indeed, quite resemble those of A. sol, and, 

 for that matter, those of many other Rhizopoda. Max 

 Schultze records an observation of three to four, up to as 

 many as twenty corpuscles [query nucleoli ?), as contained 

 in the nuclei. What their significance may have been 

 appears doubtful to HertAvig and Lesser. Carter,^ however, 



1 Carter, 'Ann. Nat. Hist.,' p. 282. 



