298 On the Development of the Pollinium in Asclepias. [Nov. 27. 



sorbed at an early period and the mother-cells themselves in 

 consequence float freely about in the loculus quite separate from 

 one another. Asclepias therefore appears to present at first sight 

 in the period of the resolution of its tapetum a closer analogy to 

 the Monocotyledons than to the group of which it is a member ; 

 since the pollinium, which consists among other parts of the 

 persistent though altered walls of the mother-cells, comes ulti- 

 mately to lie in the cavity formed by its resolution. Inasmuch 

 however as the period of its resolution is coincident with that of 

 the dehiscence of the anther-loculus I believe that it more closely 

 approaches the type of its own group than that of the Monocoty- 

 ledons, though it differs from both so far as we know of them at 

 present. It is further an important feature that there exists in 

 the anthers of Asclepias no provision which shall determine their 

 dehiscence, such as takes place in other plants by the reticulate 

 thickening of the walls in a layer of cells immediately internal to 

 the epidermis and extending round a portion of the area of the 

 loculus, i.e. the so-called "endothecium" of Purkinge 1 . Schleiden's 

 statement (loc. cit.) that the portion which disappears is dry and 

 elastic, and is cast off as a valve is obviously inaccurate on this 

 point. The nearest instance which I have been able to find to 

 the type which they exhibit is a case described by Hofmeister in 

 which the anther-lobes open at the apex by a pore which results 

 simply from the destruction of a small portion of tissue at this 

 spot, but probably other instances also will not be wanting when 

 we have more extended knowledge on this point, for as yet very 

 little indeed has been done in determining exactly the various 

 modes in which the dehiscence of the anther takes place in 

 different plants. 



(4) On some micro-organisms and their relations to disease. 

 By G. F. Dowdeswell, M.A. 



1 Be Cellulis Anther arum fibrosis, 



