75 



pendages is merely coloured by its action, frequently of a 

 purple-red. The membrane and its coating are generally si- 

 milarly affected, but in some cases, as in Beloperone oblon- 

 gata, the membrane is coloured purple-red and its coating yel- 

 lowish-brown by sulphuric acid. The outer tunic is coloured 

 of a dark brown by iodine, and the inner membrane is said to 

 take no colouring from a solution of iodine, like cellular mem- 

 brane in general (which, however, cannot be generally asserted. 

 Rep.}. The membrane of the outer tunic is sometimes of 

 greater, sometimes of less consistence, not only in various 

 plants, but at times even at different parts of the same vesicle, 

 for instance, at the apertures ; but the coatings with which the 

 membrane is covered vary considerably. This subject is 

 treated in a very elaborate manner, and by employing high 

 powers of a good microscope M. Fritzsche has succeeded in 

 bringing to light a vast number of new and interesting facts 

 which are illustrated in the annexed plates in large and beau- 

 tiful drawings. It is not possible for me to enumerate in this 

 short report the essential facts respecting these coatings of the 

 outer tunic ; I can only communicate the most important, and 

 for the remainder I must refer to the memoir itself. 



In several Malvaceae the outer membrane is equally densely 

 covered with a layer of transparent, cylindric, apparently solid 

 granules, standing erect, side by side, which give it a granular 

 appearance ; the granules seem to be connected by a distinct 

 substance ; in other plants however this is not the case. In 

 Chrysanthemum carinatum a membranous coating distinct from 

 the granules occurs. At times the granules do not cover the 

 entire surface of the membrane, at times they are placed re- 

 gularly and connected with one another by bands, at others 

 they are free and more or less regular. In Plantago capensis 

 the granules are irregular, and also in irregular position. Free 

 large equidistant granules have been observed in Jatropha 

 pandurcefolia. When the granules are united by ligaments, 

 pollen-like connexions originate on the surface of the outer 

 membrane, as in Ruellia formosa. The occurrence of spines 

 on the membrane is connected with this granular coating. In 

 Malvaceae the spines are sometimes seated on the cylindrical 

 granules, and may be separated from them ; it is probable that 

 they have no direct connexion with the outer tunic. In some 



