172 



PSYCHE. 



[February— March 1SS9. 



linators to the flowers, by luring prey to 

 the digestive apparatus of some carni- 

 vorous plants, or by maintaining upon 

 the plant a body-guard of pugnacious 

 insects, which more or less efficiently 

 protect it against certain of its enemies. 



Since the time of .Sprengel (29), 

 it has been well known that many flow- 

 ers contain glands which secrete nectar 

 as a source of attraction to insects able 

 to cross-pollinate them. The occurrence 

 of this fluid was known long before his 

 day, but its use was either not investi- 

 gated, or misunderstood. Indeed his 

 keen insight into its raisoti d'etre was 

 scarcely appreciated for three-quarters 

 of a century, until Mr. Darwin took the 

 subject in hand in his classical woi^k on 

 the pollination of orchids. To-day, how- 

 ever, Sprengel's views, cleared and 

 somewhat broadened, and carried into a 

 thousand little details that he had not 

 followed out, are contested by very few 

 persons. So fiir as our purpose is con- 

 cerned, nothing further need be said of 

 floral nectar, since the structure and 

 habits of ants are such as to practically 

 debar them from any important rOle in 

 pollination. In fact entomophilous 

 plants usually teem with devices for pre- 

 venting their access to floral nectar, — 

 for which, very naturallv, thev have a 

 great liking. 



The relation of extra-floral nectar to 

 the fructification of plants was, I believe, 

 first clearly pointed out by Delpino, 

 (6, 86), who coined the terms "nup- 

 tial" and "extra-nuptial" to indicate on 

 the one hand that which attracts polli- 

 nators, and on the other, that which is 



of no value in this respect. These 

 terms are much less objectionable than 

 "asexual" and "sexual," the former of 

 which has recently been used by Kny 

 (13) as synonymous with extra-nup- 

 tial. With nuptial nectar secreted out- 

 side the flower, we have quite as little to 

 do as with that secreted within it, for the 

 reasons already indicated ; but the sub- 

 ject of extra-nuptial nectar and its rela- 

 tion to ants, is deserving of a much fuller 

 discussion than can be given to it here 

 without going into details to a tiresome 

 length. 



W^ithout an undue amount of search- 

 ing, I cannot say when or by whom it 

 was first observed that certain flowers 

 produce nectar outside of their flowers, 

 bvit it has certainly been known for a 

 long time. Hall, a pupil of Linnaeus, 

 had seen the extra-floral glands of various 

 plants (II, 266). Kriinitz (14), whose 

 work I know only from references 

 in Sprengel and elsewhere, observed 

 bees at the stipular nectaries of Victa^ 

 over a century ago, and similar obser- 

 vations had undoubtedly been made, if 

 not heeded, even earlier. But the first 

 careful investigations into organs of this 

 sort, and their secretions and uses, were 

 made simultaneously but independently 

 by Delpino (6 and 7) in Italy, and Belt 

 (2), in tropical America. While 

 other observers have contributed many 

 isolated facts to the knowledge of these 

 organs in the fifteen years since the ob- 

 servations and conclusions of these nat- 

 uralists were published, the task of 

 following up and systematizing the dis- 

 tribution of protective nectar has de- 



