486 The University Science Bulletin. 



destroy the fibrin which is formed.-^ In Hquid media they show no 

 evident activity. 



While these experiments are interesting for the understanding of 

 the general problems of the genesis of connective tissue, their 

 broader significance lies in the new view they present of life in the 

 organism. They show that the continuous activity consistent with 

 life is not a property of these nonfunctioning cells. There must be 

 long periods of time when the connective-tissue cells show no ac- 

 tivity. Life must be, therefore, wholly a part of the functioning 

 systems, the glands, the muscles, the brains, etc. In early life, how- 

 ever, this cannot be true. The whole problem of life in the early 

 embryo is centered about an excessive metabolism and an active 

 proliferation of the undifferentiated cells of this earlier period. 



Many years ago Hofmeister, Sachs and De Bary had already 

 shown that cellular proliferation is not a primary factor in the 

 growth of plants. They thought that the mass forms in growing 

 plants before it breaks into cells. That the same is true for animals 

 has been clearly enunciated by Whitman, Adam Sedgwick, E. B. 

 Wilson and others. In development, cellular growth, division and 

 differentiation are not primary factors, but they are again secondary 

 to other more formative forces. Driesch looked upon this force as 

 something apart from nature which cannot be solved. Others have 

 not looked at it in this sense. They have considered that this early 

 development is the result of certain reactions which occasion such 

 a primary building. Many general physiologists have attempted to 

 arrive at its solution through the study of colloidal swelling. It is 

 evident, however, that such study cannot attain directly to this goal. 

 At the best they can only indicate analogies. It occurred to me to 

 attempt the solution by another method. The above studies were 

 made with connective-tissue cells of adults and the mesenchyme 

 cells and heart-muscle cells of older embryos. No careful compari- 

 son had been made of these cells with those of the younger embryos. 

 In the younger embryos it is well known that the mesenchyme cells 

 form no extracellular fibrils, but grow actively to form a cellular 

 syncytium. The fibrils appear only in later embryonic and adult 

 life. 



THE BEHAVIOR OF THE CELLS OF THE YOUNGER EMBRYOS. 



As I have cited in a previous article, M. R. and W. H. Lewis, in 

 1911,^^ noted an active movement and growth of cells in liquid 

 medium such as simple salt solution. This, as I have just stated, is 

 not true of the adult connective-tissue cells. Harrison^^ in analyzing 



