Growth of Organs in Culture Media. 135 
extended in Harrison's laboratory the use of fibrin and blood 
serum as a culture medium to the growth of various mammalian 
tissues. Other investigators especially Carrel and his collaborators 
have within the last nine months taken up these studies and grown 
tissues in fibrin as well as in agar. We also resumed recently our 
former experiments and here we wish to report briefly a few of our 
results as far as they concern the relative importance of stroma 
and parenchyma in the tissue growth in gelatinous culture media: 
A. After transplantation in vitro as well as in vivo, the central 
parts of stroma and parenchyma become necrotic, only the peri- 
pheral parts remaining alive. The extent of this central necrosis 
varies in different organs; it is, for instance, greater in the case of 
the kidney than in the case of the testicle. 
B. In regard to the relative importance of stroma and paren- 
chyma in the growth of certain organs in coagula we notice certain 
differences in various organs. 
1. In the ovary of the guinea pig and rabbit either the whole 
piece becomes necrotic or in other cases the connective tissue 
and some follicles of the cortex remain entirely or partly alive. 
The epithelial covering of the ovary remained alive and even pro- 
liferated in a few cases. Mitoses in stroma or parenchyma cells 
or distinct ingrowth of connective tissue or epithelium into the 
coagulum were not observed. The greater part of the tissue 
became necrotic. 
2. In the case of the testicle of the rabbit the peripheral 
alveoli usually remain alive without however any new formation 
of spermatozoa taking place. An irregular development of some 
epithelial cells into multinucleated giant cells may occasionally 
be observed. An outgrowth of the parenchyma into the coagulum 
does not occur, while the connective tissue can grow very actively 
into the coagulum. 
3. In the case of the kidney an outgrowth of connective tissue 
into the coagulum was a very frequent occurrence especially in 
cases in which in the periphery of the transplanted piece a part 
of the connective tissue capsule had remained adherent to the 
parenchyma. The tubular epithelium in the periphery of the 
transplanted piece usually remains alive. Growth in the paren- 
chyma takes principally place within the area of the transplanted 
