728 NATURAL SCIENCE. r,F.c.. 



The Study of Living Protoplasm. 



In Biology the study of life in its simplest manifestations con- 

 tinues to attract the attention of many investigators, and important 

 progress is being made. Dr. W. Flemming, of Kiel, has a short 

 paper in the Anatomischer Anzeiger (vol. vii., pp. 758 — 764), in which 

 he combats the idea upheld by some authors, that the well-known 

 network observed in the nucleus of certain cells is a false appearance 

 due to accidental and secondary changes in the material during 

 preparation. Dr. E. G. Balbiani (Ann. Micrographie, vol. iv., 

 pp. 449-489, pi. iii.) has studied the nucleus from another point 

 of view, namely, in reference to its influence on the growth and 

 reproduction of the cell. Dr. E. B. Wilson [Anat. Anzeig., vol. vii., 

 pp. 732-740) has been experimenting on the developing egg of 

 Amphioxtis, tearing asunder the segments at various stages in the 

 subdivision, and trying the effect of allowing these parts to continue 

 their development separately. 



Dr. Balbiani's investigations were conducted by cutting up the 

 protozoan Stentoy ccernleus, and observing the process of regeneration 

 in the various pieces. He finds that wounds are soon obliterated, 

 and that each fragment becomes a new Stentor whether or not a trace 

 of the nucleus happens to be preserved. The merest trace of a 

 nucleus accelerates repair, but, at the same time, the effect of its total 

 absence is not appreciable until this repair is tolerably advanced. 

 Even when present, indeed, the reconstitution of the nucleus is the 

 last act in the process of regeneration. For the complete restoration 

 of all the parts, however, Dr. Balbiani^finds that the constant presence 

 of a nucleus is essential : and he has often observed the death of 

 incomplete specimens, marked by the spongy character of the 

 protoplasm with water forming numerous small vacuoles. He 

 has also sometimes noticed a curious tendency, during regene- 

 ration, to a multiplication of the organism by division : and he 

 believes that the nucleoli are exclusively concerned in sexual 

 reproduction. 



Dr. Wilson's results are very curious. If an egg of Amphioxus 

 that has just segmented into four parts be taken and subdivided into 

 its components, each will usually continue to develop, and will 

 eventually give rise to an oval free-swimming larva one-fourth the 

 normal size, but otherwise quite ordinary in appearance. If 

 this 4-celled stage be allowed to fall into two pieces, each 

 half not infrequently develops successfully, and gives rise to an 

 embryo of half the normal size. Experiments, however, seem to 

 show that if the egg be split into pieces at its 8 celled stage, none of 

 these segments do more than acquire cilia, and swim about actively 

 in their simple state ; whtle, sooner or later, all of them die. 

 The same phenomenon has been observed by Dr. Driesch in 

 Echinoderms. 



