343 



along the spa.dix, thus detaching the inner coils of the spathe from 

 their grasp upon the anther cells. A copious discharge of mucus from 

 the walls of the spathe causes the released pollen to stream down into 

 the cavity below, converting the limpid liquid into a turbid, soup-like 

 mixture. Every portion of the interior is soon bedaubed with a farina- 

 ceous paste, upon which the swarming larv.i^ live and feed riotously. 

 They finally pupate and transform to ])erfect beetles. In the meantime 

 the diseased spot in the spathe completes its growth and drops away, 

 leaving a yawning orifice, through which other saprophagous insects 

 gain an entrance and add their increase to the swarming ])()pulation of 

 the flower. Prominent among these is a tly maggot, similar to those 

 which infest fungi. This maggot feeds upon tiie ri})euing parenchyma 

 of the floral envelope and destroys it. The liquid within the cavity 

 becomes ])utiid, and finally escapes through the breaking down of the 

 containing walls. 



The brood of Macrostola beetles, by this deifiolition of their domicile, 

 are driven forth to mate and betake themselves to neighboring flow- 

 ers, where they repeat the process just described. They bear with 

 tliem in the pollen ])aste with which their bodies are plentifully 

 bedaubed, the material necessary for the frnctification of the new 

 inflorescences into which they enter. 



The part played by the rot-fungus is an important one, equally 

 advantageous to the beetles and to the plant. It aids the former by 

 flrst softening the tissues of the spathe, thus allowing the beetles to 

 advance in their passage into the flower-case, and afterwards harden- 

 ing and for the time being effectually closing the entrance against 

 other intruders. After the Macrostolas, in undisturbed possession of 

 the flower-case, have accomplished the fertilization of the stigmas and 

 released the i)ollen, the fungus in maturing breaks the seal of the 

 ])lant and admits destructive insects. The aroid thus secures the 

 expulsion of its pollenizers as well as the proper ripening and dissemi- 

 nating of its seed. 



Observations upon the fertilization of nroids are not often met with 

 in botanical literature. The flowers of the more common northern 

 species have been studied by various authors, but the tropical forms 

 have been seldom examined in their native habitats, and most of the 

 observations upon their methods of fertilization have been made in 

 European greenhouses. 



The flower-cases of many species exhale powerful, often foul and 

 putrescent, odors, which attract scavenger insects of various kinds, and 

 slugs, also, being i^articularly abundant in greenhouses, have often been 

 observed creeping about the flowers. Not a few of the records made 

 under these unnatnral conditions add but little to our knowledge of 

 the manner in which tlie fertilization of these plants is accomplished 

 in the tropical forests where they are at home. 



The treatise of A. Eugler upon the arrangement of the sexual organs 



