250 



SCIENCE-GOSSIP. 



THE EVOLUTION OF THE ANIMAL CELL. 

 By Joseph Smith, M.R.I. A., F.L.S. 



' I 'HE eminent biologist, Hertwig, when consider - 

 ing the morphological properties of the cell, 

 preludes his considerations by stating that "the 

 cell is an organism by no means a simple one, 

 being built up of different parts or constituents 

 which for the greater part elude our observation 

 at present ; and to ascertain with accuracy the 

 true nature of which will remain a problem for 

 biological research for a long time to come." 

 Such is the summary on cell structure to the 

 present time, and it leaves us somewhat in the 

 same happy position as were the observers of 

 biological phenomena of the last century, yet the 

 advances which have within the last few years 

 been made in biological investigation, and the 

 consequent results placed before the thinking 

 community, should increase our appreciation of the 

 interest which surrounds the phenomenon of life. 



The parts which constitute the body of the 

 animal and those which form the tissue of the 

 plant, although differing in shape and method of 

 growth, are now recognized as being both built up 

 by the aggregation of a number, generally of a 

 considerable number, of elements which have been 

 variously termed constituting or histic elements, 

 anatomical elements, and cells. Plants and 

 animals, therefore, are constituted respectively of 

 similar elements possessing the same fundamental 

 structure, a feature which induces biologists to 

 regard such construction, the result of this aggrega- 

 tion of elementary units, as cell structure. Each 

 of these elements in reality represents a living 

 particle, and cannot, therefore, be considered 

 otherwise than as a living being. They possess 

 and enjoy all the essential properties of such 

 a being. Therefore, the animal and plant should 

 be regarded from an anatomical point, as a federa- 

 tion of those elements, varying more or less in 

 their form and attributes, their activity being con- 

 sidered physiologically as the consummation of 

 their individual existences, co-ordinated towards 

 a common end. This idea of the living being, 

 the only one which finds itself in harmonious 

 relation with the legitimate requirements of modern 

 science, therefore implies a knowledge of those 

 primary parts which in the aggregate form the 

 animal body and vegetable tissue. The study of these 

 elementary units falls within the sphere of all those 

 who desire to acquire any knowledge of the vital 

 phenomena which surround us, whether such 

 investigations be undertaken in connection with 

 health or disease ; consequently the subject is one 

 the botanist, zoologist and physiologist must 

 participate in to enable each to acquire any 



correct knowledge of the special branch of study 

 in which he finds himself engaged. It is in the 

 cells ( 1 ), to which the anatomist reduces both plant 

 and animal organisms, that the vital functions are 

 executed, they, the cells, being, according to 

 Virchow, the vital elementary units. The cell, 

 moreover, is the axis on which the science of 

 Histology, which is the examination of the minute 

 construction of the animal body, rotates ; it is the 

 basis of the comprehensive study of minute 

 anatomy in both the animal and vegetable 

 kingdoms. 



The original idea conceived by the word cell, as 

 used scientifically, has much altered during the 

 second half of the present century, and this is 

 chiefly attributable to the investigation which has 

 been made. It is not in any wise improbable that 

 our knowledge on this point may be considerably 

 increased by the better and more delicate methods 

 of investigation arising from the improved optical 

 instruments now available. These may eventually 

 enrich us with an entirely new series of concep- 

 tions, so that the idea as at present conveyed 

 by the term cannot be regarded as final or 

 perfect. 



Before Schleiden the investigation of cells 

 was suggested to Malphigi (-) and Grew ( s )< 

 by the study of plant structure. Caspar Fredk. 

 Wolff ( 4 ) and Oken ( 5 ) also investigated the 

 development of plants, and endeavoured to de- 

 monstrate that their original structure was due 

 to the aggregation of cells; but Treviranus (°) 

 showed that vessels developed from cells, that a 

 systematic arrangement in rows existed, that a 

 transformation of cells took place, and finally 

 resulted in a rupture of the partition walls. 

 Mohl some years afterwards established this as 

 a scientific fact. Schleiden was the first to- 

 demonstrate the cell theory in connection with 

 plants ( 7 ), when he endeavoured to explain the 

 mystery of all formation. The discovery which 

 Brown made during his investigation on orchids ("*), 

 that nuclei existed in some of the cells, was the key 



(i) "The Cell Outlines of General Anatomy and Phy- 

 siology," by Oscar Hertwig, translated by Campbell. 

 (London, 1895.) p. 1. 



( 3 ) " Anatome Plantarium." 



( 3 ) " The Anatomy of Plants." 



( 4 ) "Theorie von Generation" (1764). 



(5) " Lehrbuch der Naturphilosophie." 



( 6 ) C. L. Treviranus vom inwendigen Bau der Gewiiche, 

 !So6. „ . , 



(?) Matthias Schleiden : " Beitrage zur Phytogenesis. 

 Miiller's Archiv, 1830. "Principles of Scientific Botany," 

 translated by Lancaster, 184.9. 



( B ) R. Brown : " Observations on the Organs and Modes 

 of Fecundation in Orchideae and Asclepiadeae." " Transac- 

 tions of Linnean Society." London, 1833. 



