170 WAK.U10N H. LEWIS AND MARGARET II. LEWIS 



Sinuhvall ('12) ohiaiiiod growth of nnisele tissue from the 

 ciubiTos of guinea i)igs 2 cm. iu lougtli. He found three main 

 types of eells, (a) elongated si)iii(lle forms, (I)) polygonal, and 

 (c) giant cells. He also observed every gradation between thevse 

 three types of cells. The elongated .spindle forms described by 

 Sundwall evidently corresi)ond to the isolated fibers and myo- 

 blasts which are frequently abundant in our cultures. The 

 polygonal and giant cell forms correspond perhap.s to the more 

 irregular nmltinuclear pieces of muscle buds that we sometimes 

 find when the connection between the muscle bud and the ex- 

 plant becomes broken, Sundwall does not seem to have found 

 in his cultures the large muscle buds which are so characteristic 

 of our cultures. 



Congdon ('15) observed in plasma cultures the outgrowth of 

 premuscJe cells from the limb buds of seven day chick embryos. 

 The cells were in the form of much elongated spindles. The 

 outgrowth was rather scanty and not nearly so abundant as 

 are the spindle shaped myoblasts in our cultures in Locke's 

 solution. 



Levi ('10) has recently described in a few words the fact that 

 he obtained the outgrowth of striated muscle fibers of chick 

 embryos in plasma. He gives the impression that the outgrowth 

 of the skeletal muscle corresponds more or less to that of the 

 heart muscle with which his paper is more especially concerned. 



Previous to this M. R. Lewis ('15) briefly described this out- 

 growth of skeletal muscle in Locke's solution in her paper deal- 

 ing with the rhythmical contractions exhibited by some of the 

 isolated skeletal muscle fibers found in these cultures. 



It is possible that cross striated muscle fibers grow much 

 better in Locke's solution than in other media since among the 

 numerous contributions to tissue culture so little has been said 

 of cross striated muscle by other observers who have confined 

 themselves mostly to plasma diluted with water or Locke's 

 solution as a culture medium, while we have used Locke's solu- 

 tion with or without the addition of other substances. The 

 outgrowths of muscle in Locke's solution present such striking 

 features, and they are so characteristic in shape as well as so 



