48 OLIVE SWEZY. 



albumen alone and with mixtures of albumen and muscle tissue 

 extract, the latter being prepared from embryo chick tissue and 

 added to the albumen either before or after making the culture. 

 Egg albumen coagulates to a more or less firm consistency and thus 

 gives one of the conditions apparently requisite for the growth and 

 activity of the tissue cells. 



Owing to the viscosity of the albumen, considerable care is 

 necessary in handling the specimens when it becomes needful 

 to transfer the culture to a fresh medium, the usual method of 

 procedure being to cut away the old albumen with a sharp knife. 

 When, as is frequently the case, the outgrowth seemed to be 

 mainly on the surface of the glass, and thus could not be trans- 

 ferred in the usual way without the loss of the greater part of 

 the growth, another method was used. Inverting the cover glass 

 the albumen was removed with forceps and pipette, several 

 changes of Ringer's solution successively placed over the culture 

 and, after removal of this, a fresh drop of albumen was added to 

 the culture and it was again sealed up. 



The latent period, before the beginning of activity of the 

 culture, lasted from half an hour to several days. Usually, in 

 good preparation, active amoeboid movements began within half 

 an hour after being put on the slide. At that time along the 

 border of the tissue could be seen the elongated, outpushing cells 

 forming a fringe along what was before a clear cut outline, with 

 a few scattered cells lying at some little distance from the main 

 mass. These cells displayed very active amoeboid movements 

 that are less common in the older cultures though still present to 

 some extent. When these cells are chilled or disturbed they 

 contract and become rounded. On a number of cultures groups 

 ■of cells showed long clear processes extending outward, some- 

 times branched, with the ends breaking up into short filaments. 

 These were in all cases cultures which included portions of the 

 brain or spinal cord from a four-day chick. An attempt was 

 made to photograph one of these cultures but the length of time 

 necessary was sufficient to chill the slide and, on examination, 

 it was found that the processes had all been retracted. Subse- 

 quent incubation had no efTect on the culture, though disinte- 

 gration did not take place for several days. In all the cultures 



