46 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nucleoli of other nuclei. No nuclein was demonstrable in the protoplasm 

 of the cell. The male cells have in proportion to their mass of protoplasm 

 a larger nuclear mass than the female cells. The fertilized ovum has 

 thus, in proportion to its other contents, more nuclein than the unfertilized. 

 In the unfertilized egg-cell large quantities of nuclein are probably present 

 in extremely fine distribution. In this connection, Strasburger suggests that 

 parthenogenetio ova may be found to be characterized by relative pre- 

 ponderance of nuclein. 



Primitive form of Metazoa,* — Prof. W. Salensky contributes an in- 

 teresting and suggestive discussion of the much debated question as to the 

 nature and origin of the primitive Metazoa, His chief conclusions are 

 summed up as follows : — 



1. The primitive form of Metazoa, or more precisely, of the Hetero- 

 plastids, may be regarded as a Volvox-like vesicular flagellate colony, 

 nourishing itself in animal fashion, reproducing like a Volvox, and 

 exhibiting like it certain individual deviations in its development. 



2. From the vesicular primitive form, in the course of the premature 

 liberation of a series of generations, a gastrula results, in which the 

 germinal cells are partly modified into endoderm, and partly persist as 

 they were, so that the primitive genital cavity (genitocoele of Salensky) 

 becomes enteric -f- genital or a phagogenocoele. This genitogastrula form 

 is provided with an opening. 



3. The gut-cavity of the Metazoa is homologous with the brood-cavity 

 or genitoccel of the primitive form. The blastocoel of the Metazoa is a 

 new formation, which only becomes properly developed in the true 

 Metazoa. 



4. The blastopore is the homologue of the primitive aperture of the 

 Volvox colony. Its closure is nothing but a reminiscence of the closure of 

 the Volvox aperture. 



5. Difterent forms of blastula are not homologous with one another. 

 Schizoblastulae are nearest the primitive form. Gastroblastulae are derived 

 from the primitive type by a process of accelerated differentiation. 



p. KistologT-t 



Studies on the Cell.t— Herr E. Altmann states that he finds in the 

 cells of animal tissues small bodies, which he calls granules ; they ouly 

 become visible after the tissues have been treated with xylol, alcohol, 

 colouring matter, picric acid, alcohol, bergamot oil, and xylol balsam in 

 succession. The granules are present in large numbers, and appear to 

 increase by division, though it is not certain whether this is the only 

 mode. The author compares them to the lowest organisms, bacteria being, 

 in his opinion, not true cells. 



Fundamental Condition of Equilibrium in Living Cells.§ — At the 

 moment of formation the cell-membrane of animal and plant cells is thin 

 and plastic, and M. L. Errera points out that it is in the condition of a 

 soap-bubble, and is, like it, so light that the action of gravity may be 

 neglected, and that it arranges itself consequently only under the influence 

 of molecular forces. Admitting this, it is possible to connect the architec- 

 ture of cells with molecular physics. 



* Biol. Centralbl., vi. (1886) pp. 514-25, 



t This section is limited to papers relating to Cells and Fibres. 



I ' Studieii iiber die Zelle,' Heft i., 53 pp. and 1 pi., Leipzig, 1886. 



§ Coinptes Rcndus, ciii. (1886) pp. 8'22-4. 



