THE NECTAR GLAND IN CACTI 153 



This type of nectar gland stands in contrast with that from 

 which the exudate is set free either directly from the free surface 

 of the secreting cells, as appears to be the case in Vicia (Stockard 11 ) ; 

 into preformed ducts (as in certain monocotyledons, Schniewind- 

 Thies 12 ), into intercellular spaces as a normal procedure (Pteridium, 

 Lloyd 13 ) or abnormally, in a similar situation (in the case of honey 

 dew, Bonnier 14 ). Of the latter condition and, as pointed out in 

 many instances by Bonnier, not in any way connected with insects, 

 an especially striking example has recently come to our attention. 

 In 1910 a lot of plants of three species of Manihot, which furnish 

 the rubber known as Ceara, were cut of! at the ground and brought 

 into the greenhouse, where they were allowed to lie on a bench. 

 Two species had produced fruit, from the pericarp of which large 

 droplets of nectar were discovered to exude, this a month or more 

 after the plants had been harvested. The plants lived for a year 

 or longer, without any attention whatever, and in the course of 

 several months produced new shoots and leaves, from the petioles 

 of which a great deal of nectar exuded. Both in this situation and 

 on the surface of the fruits, the nectar found escape through the 

 stomata. Some smaller plants of two species Manihot glaziovii 

 and M. piauhyensis, are now growing in pots, and these are regu- 

 larly secreting nectar from the younger internodes. We have 

 examined the tissue presumably involved, namely, that which 

 lies beneath the point of issuance of the nectar, and have found 

 no anatomical changes or structure correlated with secretion. 



In such situations, and no less in the type of glands which physi- 

 ologically are indentical with the fortuitous nectar glands of 

 Manihot, the initial escape of osmotically active materials is diffi- 

 cult to account for except on the theory of chemical change in 



11 Stockard, C. R., Cytological changes accompanying secretion in the nectar- 

 glands of Vicia faba. Bull. Torr. Bot. Club, 33 : 247-262, pi. 10-11, 1906. (Contr. 

 Dept. Bot. Col. Univ. no. 227.) 



12 Schniewind-Thies, J. Beitrage zur Kenntniss der Septalnectarien. Jena. 

 1897. 



13 Lloyd, F. E., The extra-nuptial nectaries of the common brake, Pteridium 

 aquilinum. Science, N. S., 12: 885-890. June 7, 1901. 



14 Bonnier, Recherches experimentales sur la miellee. Rev. Gen. de Bot., 8: 

 no. 85, 1896. (Ref. in Bot. Centralb., 69: 82-83, 1897.) 



