Curtis : Turgidity in Mycelia 



11 



ously bursting all of the hyphae. In transferring Penicilliunt from 

 oto 9 recovery followed in 2 to 5.30 hours, turgor 28. Changing 

 from 9 to o, recovery in 50 minutes to 1.50 hours, turgor 11 ; 

 changed from o to 14, recovery 2.40 to 7 hours, turgor 36 ; changed 

 from 14 too recovery, 55 to 1.4 1, turgor 1 1 ; changed from oto 19, 

 recovery 5.40 to 12. 18 hours, turgor 43. Botrytis o to 9, recovery 

 in 1.56 to 6. 10 hours, turgor 34, 9 to o, recovery 48 to 2.21, turgor 

 13, O to 14, recovery in 3.10 to 7.43, turgor 39. Less importance 

 is attached to these experiments owing to the frequent bursting of 

 the hyphae. However, they show that the same relations exist 

 between the turgor of the recovering plant and the test plant as 

 appeared in the preceding work. 



The result of the work was unexpected and seems to indicate 

 that a much closer relation exists between turgor and growth in 

 these simple plants at least than has been supposed. I had antici- 

 pated finding several percentages of difference between the turgor 

 force of the plant just recovering from a change of substratum and 



1 



that of a plant germinated and grown in this substratum. It ap- 

 pears from these experiments that there is a necessity of a certain 

 turgor force before growth is possible and that growth cannot 

 occur until a turgor pressure has been reached which is normal to 

 the plant growing in the given solution. That turgor is not alone 

 the cause of growth is apparent from the acceleration of the rate 

 of growth after a change of substratum. In the following state- 

 ments it will be seen that there is always a short period of slow 

 growth. The figures represent divisions on the micrometer eye 

 piece, the periods of measurement being 5 minutes. 



« 5 

 1. 



2-5 



3- 

 3- 



i-5 



2.5 



3- 



3-5 



1. 



2. 



3-5 



4-5 

 6. 



2. 



2.5 

 3- 

 3- 

 3- 



•5 

 1. 



•5 

 3- 



3 



5 

 5 



5 



Ag 



it is to be noticed that when the turgor pressure was 



enormously increased by changing from high to low concentrations 

 no growth followed but the quite uniform period of recovery indi- 

 cates that some agency other than the widely various turgor pres- 

 sure was at work and it seems quite probable, as has been sug- 

 gested by Townsend and by True, that the cessation of growth is to 



