Chap. VI. SLEEP OF COTYLEDONS. 301 



List of Seedling Plants (continued). 



Mirabilis longiflora. 



Beta vulgaris. Poljgoneae (Fam. 



179). 

 Amaranthus caudatus. Amaraa- 



thacea: (Fam. 180). 

 Cannabis satira (?). Cannabinese 



(Kara. 195). 



Solanum lycopersicum. Solanese 



(Fam. 157). 

 Mimulus, (sp. ?) Scropbularineae 



(Fam. 159) — from iuformatioa 

 -given us by Prof. Pfeff'er. 

 Alir.^bilis jalapa. NyotaginPiE 



(Fam. 177). 



Brassica oleracea (Cruciferse). —It was shown in the first chapter 

 that the cotyledons of the common cabbage rise in the evening 

 and stand vertically up at night with their petioles in contact. 

 But as the two cotyledons are of unequal height, they frequently 

 interfere a little with each other's movements, the shorter one 

 often not standing quite vertically. They awake early in the 

 morning ; thus at 6.45 a.m. on Nov. 27th, whilst it was still 

 dark, the cotyledons, which had been vertical and in contact on 

 the previous evening, were reiiexed, and thus presented a very 

 different appearance. It should be borne in mind that seedlings 

 in germinating at the proper season, would not be subjected to 

 darkness at this hour in the morning. The above amount of 

 movement of the cotyledons is only temporary, lasting with plants 

 kept in a warm greenhouse from four to six days ; how long it 

 would last with seedlings growing out of doors we do not know. 



Saphanus safivus. — In the middle of the day the blades of 

 the cotyledons of 10 seedlings stood at right angles to their 

 hypocotyls, with their petioles a little divergent; at night the 

 blades stood vertically, with their bases in contact and with 

 their petioles parallel. Next morning, at 6.45 a.m., whilst it 

 was still dark, the blades were horizontal. On the following 

 night they were much raised, but hardly stood sufBciently ver- 

 tical to be said to be asleep, and so it was in a still less degree 

 on the third night. Therefore the cotyledons of this plant (kept 

 in the greenhouse) go to sleep-4or- even s^ shorter time than 

 those of the cabbage. Similar observations were made, but only 

 during a single day and night, on 13 other seedlings likewise 

 raised in the greenhouse, with the same result. 



The petioles of the cotyledons of II young seedlings of 

 Sinapis nigra were slightly divergent at noon, and the blades 

 stood at right angles to the hypocotyls ; at night the petioles 

 were in close contact, and the blades considerably raised, 

 with their bases in contact, but only a few stood suflSciently 

 upright to be called asleep. On the following morning. 



