430 STORAGE SYSTEM 



Criiger long ago proved, by his observations on the pollination of 

 Catasetum and other Orchids under natural conditions, that the feeding- 

 tissues actually do perform the function which has been attributed to 

 them. 



In another group of tropical Orchids (spp. of Maxillaria, Bifrenaria, 

 Oncidiu/it, Pleurothallis, Spiranthes, etc.) the attractive apparatus con- 

 sists of special uni- or multi-cellular hairs, which usually occur in 

 dense masses on the labellum. According to Porsch, these hairs are 

 crammed with fat and [amorphous] protein, while protein-crystals are 

 also not infrequently present. In Maxillaria rufescens each feeding- 

 hair consists of a single cell, which is very thin-walled except at the 

 base, where the membrane is thick, strongly cutinised and brownish- 

 yellow in colour; it is at the junction of the thick- and thin- walled 

 regions that the hair is broken off' by the insects. In Maxillaria 

 ochroleuca and M. porphyrostcle, the slender basal cell of the [multi- 

 cellular] hair is supported by short thick-walled accessory hairs, which 

 keep the whole structure in the upright position. In certain cases the 

 feeding-hairs are composed of short rounded cells, which ultimately 

 separate from one another, and heap themselves up into aggregations 

 resembling masses of pollen; this condition has been observed by Janse 

 in Maxillaria Zehmanni and M. vcnusta, by Fritz Midler and Saunders 

 in Polystaehya, and by Penzig in one of the Eubiaceae (llondcletia 

 strigosa). 20i 



The alleged occurrence of floral feeding-hairs in members of a 

 number of other Natural Orders (e.g. Commelynaceae, Aristolochia, 

 Portulaca, Anagallis, Cyclamen, Vcrbascum) requires confirmation. 



IV. THE STORAGE-SYSTEM IN THE THAIIOPHYTA. 205 



Water-tissues comparable to those of land-plants are, naturally 

 enough, unknown among the Algae. Even the littoral forms of 

 Seaweed are sufficiently protected against desiccation by the water- 

 retaining capacity of the mucilage with which they are coated. The 

 gelatinous sheaths of Gloeocapsa, and the jelly-like substance in which 

 the filaments of Nostoc are embedded, likewise represent water-storing 

 arrangements which are essential to the existence of these terrestrial 

 Algae. 



Tissues for storage of plastic material were first observed in certain 

 Florideae by Wille, while Hansteen and Hansen subsequently demon- 

 strated their existence in the Phaeophyceae. In Pelvetia, Fucus, 

 Sargassum and other Fucaceae, plastic materials are deposited in the 

 so-called inner cortex or primary cortex of the phycologists, that is, 

 the zone which separates the peripheral photosynthetic system from 



