185 



lo see ir such tissues, l)el()ni>iii,^ lo (lilTei-eiil species and 

 both able lo grow and nuilliply in the sanu' cullure medium, 

 were capable of uniliniv in a physiological and iiislological 

 inlegrily. II was also observed, thai fragments of duck heart. 

 were able to pulsate through several |)assages in the chicken, 

 culture medium. 



V: 



. ^♦'^ :^- '^^^^"■^^- . 







'^aSi ' ?! 





L^5>1 



\ \ 



Fig. 41. 

 Experiment 2067. A section through the line of contact of two fragments 

 of chick embryo heart which failed to pulsate simultaneously in vitro. A 

 layer of connective tissue can be seen separating the contractile elements. 



X 175. 

 From the Journ. of Exp. Med., 1924, XXXIX, 577. 



The result of this experiment was, that it proved impos- 

 sible to obtain any physiological unition of the two different 

 fragments. 



Serial sections were made of the different cultures for 

 histological examination. A definite histological difference 

 could b(. observed in the zone between fragments, which had 

 united perfectly and pulsated synchronously as one piece, 

 and those which had not, (Fig. 41;. In the line of contact 

 of the fragments, which united in a physiological way, the 



