164 VICTOR E. EMMEL 



cultures for at least two days, after which it gradually became 

 slower and less evident. As further evidence that the cultures 

 were not unfavorable to the persistence of vital functions may be 

 mentioned the growth of mesenchymal tissue cells occasionally 

 accidentally included in the preparations. These embryonic 

 tissue cells were observed to send out cytoplasmic processes, and 

 give rise to a syncytial network in a manner comparable to the 

 descriptions by Burrows and Carrel for cultures of connective 

 tissue and mesenchymal cells from the chick embryo. 



Fixed and stained preparations of the cells in the cultures were 

 made at various intervals during the experiments and compared 

 with control preparations made at the beginning of each experi- 

 ment. The majority of both the nucleated and non-nucleated 

 erythrocytes in the cultures, including those also undergoing cyto- 

 plasmic constriction, do not during the first two days appear to dif- 

 fer essentially in either their cytoplasmic or nuclear stain from that 

 of the controls. The nuclei in some cases appear more compact 

 and take a darker stain; no special tendency toward fragmentation 

 in the nuclei was observed; the hemoglobin of both the plastids 

 and erythroblasts takes a homogeneous hemoglobin stain. 



So far attention has been directed chiefly to the evidence indi- 

 cating the extent to which the normal characteristics of the cir- 

 culatory erythrocytes may be maintained in vitro. It remains to 

 consider the occurrence of regressive and degenerative changes. 

 The non-nucleated erythrocytes as taken from the circulation 

 must naturally be in various stages of normal physiological degen- 

 eration and disintegration. On the other hand, while the life of 

 these corpuscles is presumably of short duration, it is not definitely 

 known just when and how they normally disintegrate (Howell '11, 

 p. 430), and consequently a difficulty is encountered in distin- 

 guishing degenerative phenomena in the culture as being of a nor- 

 mal or of an abnormal regressive character. It appears that dis- 

 integration of even the nucleated erythrocytes may occur in the 

 embryo. Minot ('12) describes three types of such disintegration: 

 ''1, dissolving of the hemoglobin and bursting of the corpuscle; 

 2, fragmentation; 3, vacuolization, with subsequent plasmolysis" 

 (p. 509). Considering these types with reference to the cultures 



