99 



The longitudinal growth of plants has been the subject of many 

 investigations. Early in 1727, C. J. Trew 1J made observations on the 

 longitudinal growth of the flower stalk of Agave americana, calling atten- 

 tions at the same time to the influence of temperature, light, weather and 

 atmospheric pressure. Since then a great many investigations have been 

 made in this direction. 



Ernest Meyer (1827) made observation on the growth of the flower- 

 stalk of Amaryllis Belladonna and found that growth in the day-time is 

 greater than that at night. Mulder (1829) observed in the developing 

 flower-bud of Cactus glandiflorus that the growth ceases or remains 

 slight at night, while the growth in the day-time is remarkable, reaching 

 its maximum at noon. Dommeker, a gardener in Van der Hopp's garden in 

 Amsterdam (1835) made observations on the growing flower-stalk of Agave 

 americana. He considered that the growth is chiefly affected by the 

 temperature of the air, and is therefore less at night than in the day. 

 Harting (1842) minutely investigated the growth of the intern odes of the 

 stem of Humulus lupulus, and found that the growth is greatest in the 

 hours between 7 a.m. and 3 p.m., a little slower between 3 and 11 p.m., 

 and least from il p.m. to 7 a.m. 



Weiss (1846), who observed the growth of the flower-stalk of Agave 

 Jacquiniana came to the conclusion that the elongation is least in the 

 afternoon (12 noon — 10 p.m.), rises through the night (10 p.m. — 6 a.m.), 

 and reaches its maximum in the morning. 



Kauwenhoifs observations (1867) on the flower-stalk of various plants 

 gave the following results : — 



Name. 



Total growth 

 taken as 100. 



After-noon growth 

 taken as 100. 





Day. 



Night. 



a.m. 



p.m. 



Bryonia 



Wistaria 



Vitis 



Cucurbita A 



Cucnrbita B 



Dasylirium 



59.0 % 

 57.8 „ 



55.1 „ 

 56.7 „ 



57.2 „ 



55.3 „ 



41.9 % 



42.2 „ 

 44.9 „ 



43.3 „ 

 42.8 „ 

 54.8 „ 



86. % 

 71- „ 

 67. „ 

 79. „ 

 81. „ 



100 

 100 

 100 

 100 

 100 



1) These observations and several of those which follow, are referred to by Sachs, /. c. 



