40 



HUMPHREY 



Other stock solutions were made up in which the amounts of 

 the various sahs used in a normal solution were reduced in 

 quantity one fourth and one eighth, though the quantity of dis- 

 tilled water was kept the same, 500 c.c, in all the solutions. 

 It will be noticed that from one solution the acid salt, potassium 

 phosphate, was left out with a view to testing its value as a 

 stimulus to germination. Spores of the same lot were sown in 

 the various solutions the same day they were collected ; the cul- 

 ture dishes were carefully covered and placed on a north window- 

 sill where a uniform amount of diffused light fell upon each 

 culture. In another dish that had been paraffin-coated, water 

 that had been twice distilled was placed and on the same date 

 spores of the same lot were sown. These germinated in con- 

 siderable numbers within twelve days. Some of the water used 

 in this culture was taken from the supply bottle and evaporated 

 on a slide. On examination, a precipitate of organic particles 

 was found, showing that certain compounds had passed over 

 with the water in distilling, and it was thought probable that 

 these acted as a stimulus, for the spores in this culture germi- 

 nated before those in the culture containing none of the acid 

 salt. In fact these latter seemed to show no indications of any 

 preparation for germination, such as change in color of exospor- 

 ium from very dark brown to a lighter more translucent shade. 

 The distilled water used in the preparation of the various cul- 

 ture solutions was from the same stock bottle as that used in the 

 distilled-water culture. Why spores collected at the same time 

 and sown at the same time on these two media should have 

 germinated earlier in distilled water containing organic impuri- 

 ties than in a culture solution void of one of its constituent salts 

 is difficult to account for unless in the latter we have a physio- 

 logically unbalanced solution which has been shown by Loeb ^ 

 to exercise a certain toxic effect upon certain marine and fresh- 

 water animals and by Osterhout^ in his experiments upon algae. 

 This, however, needs far more extensive investigation than has 

 yet been given to it. 



'Loeb, 1905: PflUger's Archiv, 107: 252. 



* Osteihout, 1906 : On the Importance of Physiologically Balanced Solutions 

 for Plants. University of California Publications. Botany, \o\. 2, No. 10, pp. 

 229-230. 



