298 W. AllCHER. 



a deep red. According to my measurements the diameter of 

 the nucleus was about --rro" > of the nucleolus about one 

 half that measurement ; however, as the examples were very 

 large, it is possible these may be, as a rule, over the average 

 of the dimensions of this structure. 



I must now entirely agree with Hertwig and Lesser that 

 this central body is of nuclear nature, not the homologue of 

 "central capsule;" and though I once in drawing attention 

 to the corresponding structure in Acanthocystis spinifera, 

 suggested that the inner body might be comparable to the 

 *'Binnenblase" rather than to nucleolus, I think that thelatter 

 explanation is doubtless the true one, and must hold with 

 Hertwig and Lesser that the Heliozoa of Avhich Actinophrys 

 is the first, the simplest type, thereby lose all claim to rank 

 as a freshwater group of Radiolaria. 



After giving some of the views of previous observers as 

 to the action and possible function of the large peripheral 

 pulsating vacuoles, which the authors believe do not decide 

 their being of excretory nature, they proceed to the consi- 

 deration of the pseudopodia and agree with Grenadier in 

 ascribing axile threads thereto, similar to those of Acti- 

 nosphserium. These can be more readily discerned under the 

 action of dilute acids or alkalies than in the natural state, and 

 indeed, according to Grenacher, their continuations into the 

 body, may be seen as far as the '' nucleus " ('^ centrales Blas- 

 chen" of Grenacher), more plainly than permeating the pseudo- 

 podia themselves, but Hertwig and Lesser have failed in 

 detecting them passing into the body. They argue that these 

 linear threads have indeed nowhere been seen to reach the 

 nucleus or have any relation thereto, but on this see obser- 

 vations on Acanthocystis. 



Like many other Heliozoa, as is well known, two or more 

 examples of A. sol can become fused together and can sub- 

 sequently become dissociated, and this is very frequently to be 

 seen. The authors believe the phenomenon does not re- 

 present a previous growing larger of examples followed by 

 self- division, but is truly a fusion of before separate indi- 

 viduals. They do not think it has anything to do with any 

 reproductive process, but is quite accidental, possibly enab- 

 ling the group to capture and digest larger prey, more 

 manageable for their combined powers, than for the unas- 

 sisted efforts of a single Actinophrys. i 



It is some time since that I first met with an extremely 

 large Actinophrys, habitually densely charged with large and 

 bright green chlorophyll-granules, quite like those of Acan- 

 1 ' Cienk. Archiv,' Bd. i, 227. 



