10 Curtis : Turgidity in Mycelia 



substrata are about equal, u e., 10. It is quite possible that the 

 structure of the two plants has much to do with the variation, the 

 one being essentially weak in this particular and the other septate. 

 I was interested to substitute NaCl for KN0 3 for the pur- 

 pose of determining whether the replacement of a salt that is of so 

 vital importance to the plant with one of slight value would produce 

 any pronounced results. The action of this salt was most striking 

 and it was found impossible to use only comparatively weak solu- 

 tions. Mucor would not tolerate as well a 2 per cent, solution as 

 the corresponding value of KNO s , and this often produced burst- 

 ing in Botrytis. Penicillinm was more resistant and would usually 

 withstand a change from 4 to o. The results may be summarized 

 as follows : 



Mucor in a temperature averaging 24. 5 recovered very slowly 

 in changing from a nutrient solution to 2% NaCl solution. 

 The period ranged from 3 hours and 40 minutes to 5 hours 

 and 46 minutes and the turgor was found to be 21-22 in 

 the recovering and test plant. In transferring from 2 to o 

 recovery was effected in 19 to 43 minutes, turgor force 9. This 

 higher turgor force (9) was probably due to the temperature 

 and this is to be noticed generally in all work done in the sum- 

 mer. Penicillium recovered, temperature 25, from a change of O 

 to 2 in 1.24 to 2.36 hours, turgor in all comparative tests alike and 

 ranging from 19 to 20. Transferring from 2 to o, recover- 

 ing in $6 to 56 minutes, turgor ranging from 1 1 to 12. Changed 

 from o to 4 solution, recovery 1.55 to 2.50 hours, turgor 29-30; 

 transferred from a 4 to o, recovery in 3 1 to 70 minutes with turgor 

 force as stated above. Botrytis, transferred from o to 2<fo solution, 

 recovered in 1.40 to 3.10 hours, turgor 23-24. Changing from 2 

 to o, recovering in 30 to 80 minutes, turgor 13. These tests show 

 the same results and general relations as those found in Tables I 

 and II. The excessive turgor pressure is manifestly due to the 

 injurious and retarding influence of the NaCl upon the rate of 

 growth. 



A summary of the results obtained with the higher concentra- 

 tions of the KNO3 nourishing solutions is given below. Penicil- 

 lium was found to have the greatest power of adaptation and would 

 sometimes withstand a transfer from 19 to o solution without sen- 



