THE REACTION OF EMBRYONIC CELLS TO SOLID 



STRUCTURES 



R0S8 C;. HARRISON 



Osborn Zoological Lnhoratorij, Yale University 



FOURTEEN FIGURES 



It is generally recognized that the movement of cells and cell 

 masses is an essential factor in morphogenesis. ^ The most 

 obvious movements concerned in the development of the Metazoa 

 are those of cell aggregates, but these are often complicated by 

 their association with growth or increase in mass. On the other 

 hand, the movements of single cells, involving growth only to a 

 very slight extent, are less complex and, at the same time, with 

 our present methods of tissue culture, are readily amenable to 

 observation and experiment. The mechanism of this move- 

 ment is the streaming of the cell protoplasm, and the ontogenetic 

 results depend upon the physical properties of the protoplasm 

 itself and the stimuli which act upon it. 



The importance of such factors in development was fully 

 recognized twenty years ago by Roux^ in his experimental study 

 of the behavior of isolated cells of the frog's blastula, and by 

 Herbst'* in his 'Reizphysiologie.' Even before this Loeb** had 

 considered the tropisms of cells, and had shown that the arrange- 

 ment assumed by certain chromatophores in the fish embryo is 

 dependent upon a stimulus emanating from the circulating blood. 

 Somewhat later Driesch^ also took up the question and found a 



1 The various types of movement occurring in ontogeny ha^e been carefully 

 classified by Davenport in his "Preliminary catalogue of the processes concerned 

 in ontogeny." Bull. Mus. Comp. Zool. Harvard Coll., vol. 27, 1896. 



2 Cytotropismus. Arch. f. Entw. Mech., Bd. 1, 1894; Bd. 3, 1896. 



3 Biol. Zentralbl., Bd. 14 and 1.5, 1894, 1895. Also Formative Reize, Leipzig, 

 1901. 



' Jour. Alorph., vol. 8, 1893. 



= Arch. f. Entw. Mech., Bd. 3, 1896. 



521 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 17, NO. 4 



