Maech 18, 1921] 



SCIENCE 



261 



SPECIAL ARTICLES 



AMCEBOID MOVEMENT, TISSUE FORMATION 

 AND CONSISTENCY OF PROTOPLASM^ 



1. In 1901 we found througli testing by 

 direct means the consistency of the proto- 

 plasm that in. the blood cells of Limulus 

 amcsboid movement depends primarily upon 

 alternating changes ra the consistency of the 

 protoplasm, a phase of liquefaction being fol- 

 lowed by a phase of hardening. There may be 

 added to these changes in consistency changes 

 in surface tension.'- Subsequently we showed 

 in experiments in which we likewise tested 

 the consistency of the cells directly that the 

 consistency varies under different conditions, 

 that these variations correspond not only to 

 the pseudopodial activity, but also to the 

 agglutinability of the blood cells and to the 

 formation of tissue like structures from 

 previously isolated cells,^- ^ that these changes 

 due to stimulation explained the stereotropism 

 of tissue cells,^' ^ that they played a part in 

 the processes of inflammation,'- ^ phagocyto- 

 sis,* and thrombosis.^' "■ '■ ^ More recent ob- 

 servations in 1919 showed that it is possible 

 to vary greatly the character of the amceboid 

 movements and that the changes in the amoe- 

 boid movements correspond to the changes in 

 the consistency of the protoplasm; these ob- 

 servations suggested that the taking up of 

 fluid from the surrounding fluid on the part 

 of the cells is an important factor in these 



1 From the Department of Comparative Pathol- 

 ogy, Waahington University, and from the Marine 

 Biological Laboratory, Woods Holl. 



1 Leo Loeb, Jom. Med. Research, 1902, VII., 145. 

 3 Leo Loeb, Biological Bulletin, 1903, IV., 301. 



2 Leo Loeb, Virchow 's ArcMv., 1903, CLXXIIL, 

 35. 



* Leo Loeb, Anatomical Record, 1912, VI. 



5 Leo Loeb, Virchow 's Archiv, 1905, CLXXXV., 

 160. 



6 Leo Loeb, Hofmeister 's Beitraege s. Chem. 

 Physiol, u. Fathol., 1904, V., 191. 



7 Leo Loeb, Pfiueger's Archiv, 1910, CXXXI., 

 465. 



8 Leo Loeb, Biocliem. Zeitschrift, 1910, XXIV, 

 478. 



processes.' We furthermore showed that cer- 

 tain phenomena of wound healing can be 

 imitated in this experimental amoebocyte- 

 tissue and that the formation of giant cells 

 which takes place in sensitive cells in contact 

 with a foreign body represents an application 

 of the same principle.' Here we have to as- 

 sume that the process of liquefaction may 

 proceed so far that two cells may flow to- 

 gether. We also pointed out that variations 

 in the hydrogen ion content of the cells 

 under the influence of stimulation might ex- 

 plain these changes. 



2. A continuation of these experiments in 

 Woods Hole last summer showed that in the 

 blood cells of Limulus it is x>ossible to produce 

 graded variations in the character of the 

 pseudoiKtds and amoeboid movements through 

 graded changes in the osmotic pressure in 

 the surrounding medium. Again we find cor- 

 respondence between the consistency of the 

 protoplasm and the character of the pseudo- 

 pods and amoeboid movement. A particularly 

 great fluidity of the protoplasm could be pro- 

 duced through the use of a slightly hypotonic 

 solution of KCl. In this case the change in 

 consistency became so marked that it affected 

 not only the ectoplasmic layer of the cell, 

 but extended to the whole of the granulo- 

 plasm. There is reason to assume that these 

 changes are associated with the taking up of 

 fluid from the surrounding medium. Under 

 those conditions a very peculiar phenomenon 

 which we described previously, a circus move- 

 ment of the whole cell exoplasm as well as of 

 the granuloplasm, can be produced regularly. 

 These movements, however, take place only if 

 the temjperature of the surrounding fluid is 

 sufiiciently high. It does not occur in cells 

 kept at a temperature of 10°. 



3. Exposure of the blood cells to a tempera- 

 ture of approximately 40°-42° for a short 

 period of time produces in the periphery of 



9 Leo Loeb, ' ' The movements of the Amcebooytes 

 and the experimental production of amoebocyte 

 (cellfibrin) tissue," Washington University Stud- 

 ies, Scientific Series, 1920, Volume VIII., 3. 

 (Here a general discussion of the subject is given.) 



