768 SUMMARY OF CURRENT RESEARCHES RELATING TO 



from 40-90 per cent. After sufficient hardening the organisms were 

 imbedded, first in dilute, then in concentrated celloidin, and cut in sections 

 with the microtome. The sections were then stained with hsematoxylin. 

 The structures within the central capsule, which when intact is very im- 

 penetrable, were then readily demonstrated. The beautiful blue colour, 

 which is probably due to the oil-globules, is removed by the alcohol, and 

 the central portions appear brownish. The extra-capsular protoplasm 

 appears quite homogeneous, is stained blue by the hsematoxylin, and 

 exhibits here and there fine strands, which extend outwards from the layer 

 which gives origin to the pseudopodia, and share with the protoplasm of 

 this region fine brown pigment-bodies. 



The region which gives origin to the pseudopodia contains not only 

 small, but also large vacuoles, inclosing roundish angular spherules and 

 long strands of variable breadth, sometimes homogeneous, sometimes 

 longitudinally striated, and often with a distinct nucleus. Higher powers 

 reveal a fine transverse striation, and the roundish angular bodies are seen 

 to be cross sections of these muscular strands. Since Brandt has shown 

 that foreign bodies can only remain attached to the surface, the muscular 

 shreds found in the layer which gives origin to the pseudopodia must 

 either be remains of the bodies of animals which have forced their way 

 inwards, or, if no other remnants are to be found, they must be the only 

 portions taken up by the Thalassicola. How these ingested muscle- 

 fragments find their way in cannot be answered without further observa- 

 tion. It was noticeable that beyond a disruption of the fibrillse no change 

 was detectable. 



The spherical central capsule is bordered by a membrane penetrated by 

 numerous pores without special arrangement. On surface view the pores 

 appear to be included in a finely granular mass without pigment ; on cross 

 sections this appears to be beset on both sides with small pointed hairs, 

 which are probably minute stumps of the protoplasmic processes pene- 

 trating the pores. 



The intracapsular protoplasm exhibits three zones: an external one 

 distinctly striated radially, a broad median vacuolar zone, and a narrow 

 internal layer with indistinct radial striation. The whole medullary mass 

 appears finely granular, but higher powers exhibit a fine frothy structure, 

 particularly prominent in the outer zone. There is no radial arrangement 

 of granules, and the differentiation of keel-shaped plasmic portions is 

 wholly due to the thicker strands of protoplasm. Very delicate bridges 

 connect the keel-shaped portions. This structure is obscured in the 

 median zone by the recurrence of simple or composite vacuoles. These 

 inclose hyaline spherules containing concentrically arranged spherical 

 concretions, probably composed of carbonate of lime. 



The nucleus is roundish, and bordered by a double-contoured mem- 

 brane. It appears to be almost homogeneous, but higher powers demon- 

 strate the presence of a narrow-meshed framework. The proper chromatin 

 substance is limited to 15-20 roundish angular nucleoli, round which the 

 nuclear network is usually looser, so that they appear to be surrounded by 

 clear spaces. They are, however, connected by fine threads to the frame- 

 work. They stain very unequally. 



Artificial Development in Actinosphaerium.* — Prof. A. Gruber calls 

 attention to a neglected observation by K. Brandt, which appeared in an 

 inaugural dissertation — one of the best places for hiding observations— in 

 1877. " This division may be brought about artificially by cutting up the 



* Zool. Anzeig., x. pp. 346-7. 



