January 6, 1922] 



SCIENCE 



23 



consequently the consistency of the cell too 

 great, their motility is diminished. If it is used 

 in too weak a eoneentratjon, the spreading out 

 and solution processes are not sufficiently de- 

 layed. In an intermediate concentration of the 

 acid, the consistency is such that the migration 

 of the cells out of the piece is readily possible 

 and at the same time the cells are preserved 

 and the stereotropic reaction is retarded. But 

 ultimately the cells begin to spread out and now 

 retrogi'essive changes set in even in these favor- 

 able media. However, it may be possible to 

 keep the cells active for sis days or longer 

 even at room temperature, at which under or- 

 dinary conditions the cells spread out and be- 

 come hyaline on the first or second day. 



In this case we recognize thus as the prin- 

 cipal cause of cell death an extreme degree of 

 reactivity of the cells in contact with solid sur- 

 faces. There is good reason for assuming that 

 this reaction leads to an increased permeability 

 of the surface of the cell which reaches a de- 

 gree which is injurious and is thus respon- 

 sible for the subsequent degenerative processes. 



Conditions which prevent this extreme stereo- 

 tropic reaction tend therefore to prolong the 

 life of the cells. Acid acts in this way ap- 

 parently by increasing the consistency of the 

 cells, at least of its outer layer. 



As we have shown elsewhere * there exists a 

 striking analogy between the behavior of the 

 amoebocytes and ordinary tissue cells. Through 

 agglutination the amoebocytes produce sheets of 

 a tissue-like mateiial. After an incision in such 

 a tissue cells migrate from the cut edge into 

 the defect, in a way similar to tissue cells ad- 

 joining a wound. In both cases two factors 

 determine the direction of migration: (a) The 

 stereotropic reaction, (b) a tendency towards 

 centrifugal movement. 



During the process of movement the amoebo- 

 cytes spread out and thus produce structures; 

 totally unlike the original amoebocytes, but 

 closely resembling various tissues. A similar 

 change from agglutinated round cells to cells 

 spreading out in contact with a solid or viscous 

 substratum underlies the embryonic tissue for- 

 mation. Under the influence of mechanical 

 factors a system of fibrillation can be produced 

 in this experimental amoebocyte tissue which 



indicates the direction in which the mechanical 

 factors act. In an analogous way we know 

 that certain mechanical effects determine the 

 fibrillation in certain higher tissues. In both 

 cases the tissue formation leads to the produc- 

 tion of an elastic tension under which the tis- 

 sues are held, which latter retract after an in- 

 cision had been made. The processes of tissue 

 formation had led to the production of poten- 

 tial energy stored in the tissues. 



The transformations which we olDserve in the 

 amoebocytes in the case of tissue formation are, 

 as far as our evidence shows at present, due 

 mainlj' to two factors: (a) changes in con- 

 sistency primarily in the outer layer of the 

 cells; this depends in all probability upon a 

 taking up of fluid from the surrounding me- 

 dium and a different distribution of fluid within 

 the cell, and (b) an increased permeabilitj' of 

 the outer layer of the cell. These changes may 

 lead to degenerative processes in the cell. 



In some respects the differentiation and 

 specialization of tissue cells in higher organisms 

 has likewise the aspect of retrogressive changes ; 

 it may diminish the power of resistance of 

 these dift'erentiating cells. This suggests very 

 strongly that changes of a similar character, al- 

 though perhaps quantitatively weaker, may take 

 place in the higher tissue cells during the pro- 

 cess of tissue formation. 



Leo Loeb 

 Department of Comparative Pathology, 

 Washington University 



THE AMERICAN CHEMICAL 

 SOCIETY 



(Conlmued) 



division of chemistry of medicinal products 

 Charles E. Caspari, chairman. 

 Edgar B. Carter, secretary. 



Arsplienamine and neoarsphenamine : George 

 W. Eaiziss, Joseph Gavron and M. Falkov. 

 Arsphenamine and neoarsphenamine are indispen- 

 sable in the treatment of spiroehaetie infections. 

 The elimination of the alarming symptoms or 

 "reactions" attendant upon the use of these 

 drugs is a problem of increasing importance. 

 These have been attributed to chemical impurities 

 which the authors have tried to identify. Inci- 

 dentally, samples, of unusually high ehemothera- 

 peutie indices have been obtained. Methyl alco- 



