. 
; 
; 
1899] SOCIETY FOR PLANT MORPHOLOGY 125. 
numbers, led to the belief that the restraining influence must be 
the acid juices of the cabbage, the bean, and the hyacinth. 
Experiments tend to establish this fact more definitely. All 
the fluids tested, hyacinth broth, cabbage juice, tomato juice, 
potato broth, acid beef broths, malic acid broths, etc., were 
titrated with caustic soda and phenolphthalein so that in each 
case the exact grade of acidity which retarded or inhibited 
growth is known definitely. This paper will soon appear in full 
as part of the larger work dealing with the parasitic nature and 
life history of Wakker’s hyacinth bacterium. 
Further observations on the relations of turgor to growth: CARLE- 
TON C. Curtis, Columbia University. Experiments were under- 
taken to determine the time limit for the renewal of growth after 
changing the concentration of the nourishing substratum, and also 
for testing the turgor force at the moment of renewal. Species of 
Mucor, Penicillium, and Botrytis were used. They were grown 
i respectively a nourishing solution, a nourishing solution with 
the addition of 4,9, 14, and 20 per cent. KNO,. Penicillium in 
the solution with no KNO, had a turgor force of 7.5 (NaNO, 
being used as a test); in a 20 per cent. solution, 42.5. In chang- 
ing from 0 to 20 per cent., growth ceased for from 8 to 12 
hours. When it began the turgor force in the majority of cases 
@ppeared normal, 7. ¢., 42.5. In changing from 30 per cent. to 0, 
growth ceased for 30 to 45 minutes, when it resumed growing 
se the normal turgor force (7.5). So with the lesser changes, 
’- é from 0 to 4 per cent., recovery occurred in about one hour, 
~ tur 
“tor force normal (12); change from 4 per cent. to 0, recovery 
ee minutes, turgor 7.5, and so on. Botrytis gave prac- 
a wick * Same results. Mucor was much more sensitive, having 
than a urgor force, ues would not tolerate a change to higher 
as the oie — solution, but in other respects it behaved 
Salt solutio ers. Experiments are being conducted with other 
it would - and also ost ind higher plants. As regards KNO, 
check due " ee turgor is a controlling force in growth. The 
to cutti a ns the turgor corresponds to the shock due 
Ng a hypha, inhibiting growth for a time. 
