The Cause and Conditions of Lysigenous 
Cavity-formation. 
BY 
FREDERICK C. NEWCOMBE, Ph.D. 
Assistant Professor of Botany in the University of Michigan. 
I T has long been known that in the formation of lysigenous 
cavities during primary extension in plants there is 
a tearing apart of cells due to tension between tissues, while 
in plants in which lysigenous cavities arise subsequently to 
primary growth there is generally a collapse, but little or no 
tearing of cells. The relation of these two processes of cavity- 
formation to one another has however, so far as I know, not 
been the subject of consideration. Moreover the extent to 
which this tearing during primary growth is a determining 
factor in the duration of the life-period of the cells concerned, 
is a matter which has not been determined. 
The following pages will thus treat of these two questions : — 
i. What are the conditions of lysigenous cavity-formation 
during and subsequently to primary growth ? 
1. Would cells that are destroyed by tearing during primary 
growth live much longer if the tearing did not take place ? 
In this study the following plants have been used for 
observation and experiment : — 
Allium Cep a, L. Dahlia variabilis , W. 
Althaea taurinensis , DC. Equisetum limosum , L. 
A rchangelica sativa, Mill. Eryngium planum , L. 
Caltha palustris , L. 
Cucurbit a Pepo , L. 
Forsythia viridissima , Lindl. 
Helianthus tuber osus , L. 
[Annals of Botany, Vol. VIII. No. XXXII. December, 1894.] 
