348 



SCIENCE-GOSSIP. 



consists of " a mass of substances peculiar to it, 

 and which to a certain degree differ from proto- 

 plasm, and may be distinguished from it." 



In addition, there are present other bodies usu- 

 ally known as nucleoli, and these play a prominent 

 part in the structure of the germinal vesicles of 

 animal egg cells. They generally differ very 

 materially in their tissue from the nuclei met 

 with in ordinary tissues. These nucleoli may be 

 easily distinguished in the large eggs of fishes, 

 amphibians, reptiles, and the number of spots 

 increase during the growth of the cell until a 

 very large number are present. Whether this 

 amplification is brought about by division is not 

 at present known. The position of the nucleoli, 

 or germinal spots, as they are generally termed> 

 although the term is not correct, has not been 

 satisfactorily worked out. It is, however, clear 

 the rounded bodies more or less present in the 

 nuclei of plants and animals have been classed 

 together incorrectly under the name of nucleoli, 

 as they show material differences amongst them- 

 selves ( 2 ). Generally it is supposed these nucleoli 

 are built up of two substances, and this structure 

 has been observed to exist in Helix, Tellina and 

 Asteracanthron, as also in the Anodon, but in the 

 Asteracanthron, however, the feature becomes one 

 of special interest, since the separation into two 

 substances only begins to be visible when the 

 germinal vesicle commences to break up. The 

 resting nucleus may exhibit considerable variation 

 in all its separate parts, according to the age or 

 development of the cell. As the ovum matures 

 a novel feature in cell evolution begins to be 

 remarkable; it may be looked on as the final 

 factor in perfecting the life-history or cycle of 

 cell formation. The polar spindle, or pole cor- 

 puscle of the cell, as it is sometimes called, now 

 becomes apparent. It is a very minute object, 

 exists in the protoplasm of the cell, and is termed 

 the centrosome. In cell structure it is of the great- 

 est importance. Its functional vitality is exhibited 

 in the economy of the cell, it is the cell centre, and 

 its character during the development of the cell 

 contents, after same have been subjected to fertiliz- 

 ing influences, is highly functional. Around this 

 polar corpuscle the various cell contents arrange 

 themselves. It is entirely a micro organism, and, 

 as a rule, there is one pole corpuscle in each lymph 

 cell ; but there are exceptions to the rule, since in 

 the epithelium of the lung, and in the endothelium 



( 2 ) Flemming : " Zellsubstanz, Kern und Zelltheilung," 

 Leipzig, 1882. Carnoy : several papers in " La Cellule : 

 Recueil de Cytologie et d'Histologie generate " — "La Cyto- 

 dierese chez les Arthropodes," t. i. ; " La vesicule germina- 

 tive et les glottes polaires chez divers nematodes." See also 

 " Conference donnee a la Societe beige de Microscopie," 

 t. iii. Likewise, H. B. Lee, on " Carnoy's Cell Researches " 

 — Quart. Journ. Mic. Soc, vol. sxvi. p. 481-497. Zacharias : 

 " Ueber den Nucleolus" — " Botanische Zeitung," 1885. 

 Oscar Hertwig: " Beitrage zur Kenntniss der Bedlung 

 Befruchtung und Theilung des Thierischen Eis"— Morphol. 

 Jahrbuch, 1, h. v. 



and connective tissue cells of the peritoneum of 

 salamander larva?, two of these corpuscles have been 

 found lying close together in place of one, either 

 in the immediate neighbourhood of the resting 

 nucleus, or in the indentation of it, and immedi- 

 ately in contact with the nuclear membrane. This 

 corpuscle possesses the faculty of being able to 

 multiply itself by spontaneous division. Such are 

 the component parts of the animal cell. In the 

 first instance we have the existing vivified proto- 

 plasm in which, as time progresses, is noticed the 

 resting nucleus. Within this in due course appears 

 the nucleolus, or inner germinating spot. Other 

 substances now manifest their presence, the 

 functional characters of which may be regarded 

 as passive until the advanced stages of the egg, 

 i.e. fertilization, are reached ; and finally we find 

 existing the pole corpuscle. The cell now is 

 complete, and awaits the consummating act which 

 sets into motion that embosomed vitality which 

 eventually leads to the development of the adult 

 animal form. 



It has been suggested that elementary organs 

 exist which are not possessed of nuclei, and 

 Haeckel at one time recorded two divisions in 

 which no nuclear centre could be traced ; not that 

 such was correct, for the nucleus was invisible 

 and could not be identified on account of its 

 minuteness. Many of the plants, e.g. Algae, Fungi, 

 Protozoa, Vampyrella, Polythalamia and Myxo- 

 mycetes, all at one time illustrative of the non- 

 existence of nuclear centres, are now demonstrated 

 to possess nucleated cells. Since the discovery of 

 the human ovum it is considered as indisputable 

 that throughout the whole animal kingdom no 

 example of cell without a nucleus can be given. It 

 was against this assertion of the non-existing non- 

 nuclear cell, that the blood of mammals was put 

 forward as an illustrative example of the existence 

 of such cells ; but the blood of this group of animals 

 contains no true protoplasm, and consequently no 

 true nuclei. Moreover, they are not considered as 

 true cells, but merely the products of the meta- 

 morphosis of the developments of former cells. 

 Now it will be asked : what after all is essential to a 

 cell ? All that is essential to the cell, or elementary 

 part, is matter — matter in a living state, germinal 

 matter, and matter which is formed matter or 

 material ; with these is usually associated a certain 

 proportion of matter about to become living — 

 the pabulum or food. So that we may say in every 

 living being there exists matter in three different 

 stages : matter about to become living, matter 

 actually living and developing, and matter which is 

 formed and is therefore changeless. 



Final causes are also introduced into the 

 speculative theory surrounding the phenomena of 

 organic life, and they are almost universally 

 deemed to be the real ultimate cause of life. Some 



