ENVIRONMENTAL FACTORS 



75 





Solutions. It has been the general experience that the readily 

 culturable parasitic and hemiparasitic fungi have about the same 

 relation to strengths of solu- M r 



tions as the saprophytic forms. 

 Ordinarily, therefore, such 

 forms give abundant growth 

 under widely different condi- 

 tions of concentration of the 

 substratum. According to 

 Eschenhagen the concentra- 

 tions at which Botrytis cinerea 

 may grow under ordinary cir- 

 cumstances are as follows : 

 grape sugar, 51 per cent ; 

 cane sugar, 37 per cent; 

 sodium nitrate and calcium 

 chloride, 1 6 per cent ; sodium 

 chloride, 1 2 per cent. In the 

 culture work in the laboratory 

 it will be found, however, that 

 differences in the strength of FIG. 15. CELLS OF ERICACE/E (after Ter- 

 the culture medium will be netz), AND ORCHIDACE^E WITH ENDOPHYTIC 

 accompanied by noticeable MYC RHIZA > ALSO CORALLOID ROOTS 

 differences in the form of the fungous colony, amount of the 

 mycelium, and the character of the spores produced. 



