masses so produced, which concur to the development of 

 another individual ; and this may be, or may not be, like 

 that individual in which the secondary germ-cell or germ- 

 mass was included. 



It has been found that in proportion as the subjects of 

 anatomical investigation descend in the scale of animal life, 

 the number of the derivative germ-cells and nuclei which 

 retain their individuality and spermatic power is greater, 

 and the number of those that are metamorphosed into 

 tissues and organs less. 



Cells predominate in the tissues of the vegetable king- 

 dom, the lower members of which consist exclusively of 

 them, and have been thence called e plantae cellulares : ' the 

 lowest of all consist of a single nucleated cell. 



The animal kingdom starts from the same elementary 

 beginning : a cell- wall forms the smooth elastic and con- 

 tractile integument of the Gregarina*: a fluid with granules, 

 and a firm nucleus which sometimes contains one or more 

 nucleoli, the ordinary cell-contents, are the sole repre- 

 sentatives of organs or viscera. Yet the power of the Gre- 

 garinte to live and grow independently by assimilating fo- 

 reign nutriment, the vital contractility of their tegumentary 

 tunic, their chemical composition and their definite forms, 

 with such well-marked specific characters, in a few instances, 

 as the Greg, brevirostris and Greg. Sieboldii present, render 

 their interpretation by Kolliker as a low and primitive form 

 of parasitic animal, the most accordant with actual physio- 

 logical and zoological knowledge f. 



The Gregarina is a single- celled animal, which differs 

 from the single-celled plant by the vital contractility of its 

 tissue, and the solubility of its cell-wall in acetic acid. 

 Devoid' of mouth, stomach, or any other organ properly so 



* A genus of microscopic parasites which infest gregariously the in- 

 ternal cavities and canals of insects and worms. 



t Kolliker, ' Ueber die Gattung Gregarina,' Zeitschrift fur Wissen- 

 schaftliche Zoologie, Bd. i. p. 10, 1848, 



