45 



proceed in darkness. Detmer adds a few historical references, viz, 

 Humboldt (1704), according to whom seeds sprout more easily in 

 darkness than in light; Fleischer (1851), Heiden (1859), and Nobbe 

 (who all consider solar rays as having no action on the seeds), and, 

 finally, Plunt (1851), who considers that light retards geruiination. 



After this preliminary historical survey, Pauchon communicates 

 the results of his own experiments as to the influence of light on ger- 

 mination on the following twenty-two species of plants : 



C'rucifern' : Ijeguiuinosejp : 



Brassica napus. Aracbis hypogjipa. 



Iberls amara. Dolichos lablab. 



Lepidium sativum. Rubiace;p : 



Sinapis alba. Coffea arabica var. Rio. 



Raphauns sativum. Spilantlies fiisea. 



Rammeulace.v : Heliaiitlius aimuus. 



Delpbiiiium Consolida. , Cartbauuis tinctorius. 



Nigella sativa. MalvaceiP : 

 Cucurbitacete : Hibi^icus estuleutus. 



Ciicurbita uielo var. melon I'olygoiiace.-e : 



vert. Fagopyrum esculentum. 



Papaveracefe : Liuat-eip : 



Papaver somuiferum. Linum usitatissimum. 



F.nphorbiacejp : Bignoniacea^ or Pedaliaceae: 



Rieinns communis. Sesamum orientale. 



Gramineai: Liliace.-p: 



Zea mays. Pancratium maritinunn. 



After deducting doubtful results or failures Pauchon gives the 

 following conclusions (see p. 131 of his work above quoted) : 



(1) In 22 experiments germination occurred first in the light; in 

 26 experiments it occurred first in the dark. 



(2) Five times we obtained duplicate results favorable to the 

 light for the same species of plants {Arachis^ Zea m/ii/s, Dolic/io.Sj 

 Sinapis, and Linum). Eight times these duplicate results were 

 favorable to specimens kept in the dark {HelianthuH, Delphiti'nini, 

 Pancratium, Ricinus, and Papaoer). In one case {Linum) two re- 

 sults were obtained favoring light and two favoring darkness. 



(3) Among the 22 species of plants used in the experiments 14 gave 

 mixed results equally favorable whether placed in the light or the 

 dark. 



(4) Amoug the 8 other varieties only 1 gave negative resuhs (Cof- 

 fea) ; 3 gave results favorable to light {Cuatrhita, Spilauthes, and 

 Carthaniiis) ; 4 gave results favorable to darkness {Del phhihim. Pan- 

 cratium, Lepidium, and Nigrlln). 



It appeared to Pauchon impossible to draw any conclusion what- 

 ever from these facts. Should we be astonished at this? The prob- 

 lem is certainly much more comj^lex than appears at first sight. 



