48 HORTICULTURAL SOCIETY OF NEW YORK. 



(minimum). The average weekly evaporation rate for 

 the period from May I3th to July ist was, as given by Dr. 

 MacCullum's data, 323.8 cc. 



The seeds germinated somewhat tardily but otherwise in 

 a perfectly normal manner. With the castor bean and musk- 

 melon, after a few days in the cotyledon stage growth was rapid, 

 more so in the former than in the latter ; but growth became still 

 more rapid in both cases after July 6th. The other forms of 

 the series slowly developed a few leaves and then practically 

 ceased to grow at all. Day after day they were examined with- 

 out the detection of any difference from the condition of the 

 preceding day. The plants did not wilt and appeared healthy, 

 except for the lack of growth. There was some growth in all 

 cases during this period but it was so small in amount that it 

 was practically negligible. 



After July 6th the weekly averages of the daily 

 maxima and minima of temperature and relative humidity 

 were very close to those exhibited for the week ending 

 August 26th, which were: for temperature, 100 and 

 80 F., and for relative humidity, 95% and 59%. It is 

 at once seen that the temperature conditions were not 

 greatly different during the season of summer rains from 

 those of the spring dry season, so that the response in growth 

 of the plants, which I am about to describe, cannot be related 

 to this factor. The humidity conditions for the two periods 

 were about what was observed in the case of the evaporation 

 rate, which showed an average of 185 cc. per week during the 

 second period, i. e., a decrease to about $7% of its rate during 

 the dry season, as given previously (383.8 cc.). After the be- 

 ginning of the rains irrigation was unnecessary excepting a few 

 times when the showers were too far separated and the soil began 

 to show signs of drying out. It is, of course, theoretically pos- 

 sible that the plant responses here to "be described were caused 

 by the change from well-water to rain-water. This is not at 

 all probable on account of the fact that the saline content of 

 the well-water is mainly calcium and magnesium carbonates, 

 and that these exist in the soil in rather large amounts, so that 

 the rain-water must almost immediately become of practically 



