PHYSIOLOGY AND MORPHOLOGY OF CALIFORNIA HEPATIC^ 39 



rains and rapid desiccation following one upon the other. What- 

 ever be the cause of impairment the fact remains that almost 

 no spores germinated even under most painstaking precautions 

 as to culture conditions. To get at the root of the matter, how- 

 ever, a series of experiments is necessary in which the student 

 should duplicate as nearly as possible the conditions prevailing 

 from April i to June 15 of 1906. 



It is an unsettled question as to whether the spores of many 

 liverworts actually require a prolonged resting-period, and there 

 is still need of investigation along this line. We are familiar 

 with the fact that the spores of most xerophilous forms do lie 

 dormant several weeks before germinating but it has not been 

 shown in very many instances that this resting-period is inti- 

 mately connected with the preparation of the spore for germina- 

 tion. The writer has demonstrated beyond doubt that the spores 

 of Fossomhronia longiseta, under certain conditions, do not re- 

 quire a resting-period. Cultures were prepared using different 

 media with a view to testing, if possible, the relative influences 

 of the various media upon germination. One lot of spores col- 

 lected on January 10, 1906, were sown January 12 on pulver- 

 ized earth that had been thoroughly steam-sterilized and well 

 watered with distilled water. Care was exercised to select soil 

 on which Fossombronia grows vigorously out of doors ; this 

 was placed in a crystallization dish and covered with one half 

 of a petri dish to keep the culture as free from dust as possible. 

 A number of crystallization dishes were thoroughly cleaned 

 and then covered on the inside with a thin coating of parafiin 

 to prevent the water used from taking up any impurities that 

 might exist in the glass. In three of these, Knop's nutrient 

 solution of the following proportions was placed : 



HjO 500 c.c. 



Calcium nitrate 2.00 grams. 



Magnesium sulphate 0.5 " 



Potassium nitrate 0.5 " 



Potassium phosphate 0.5 " 



Other solutions of varying strength were employed as follows : 

 Wfi 500 c.c. 



Calcium nitrate 2.00 grams. 



Magnesium sulphate 0.5 " 



Potassium nitrate 0.5 " 



Potassium phosphate omitted. 



