(3) On the Development of the Pollinium in Asclepias. By 

 Thos. H. Corry, B.A. 



So far as I have been able to ascertain no observer has fully 

 investigated, in an adequate manner the whole mode of formation 

 of the pollen-mass or pollinium in this genus, and in the natural 

 order to which it belongs. Hofmeister 1 and Schacht 2 alone have 

 thrown some light upon its history in the early stages with how- 

 ever somewhat contradictory results, while Schleiden's 3 account of 

 it is incorrect in several respects and very fragmentary. Francis 

 Bauer, Ehrenberg 4 , Robt. Brown 5 , Adolphe Brongniart 6 , and the 

 younger Reichenbach 7 have all recorded details more or less exact 

 concerning its structure but principally in some of the later stages 

 when the flower is becoming rapidly mature. 



In the very young anther, which has the form of a very slightly 

 flattened spatula with a strongly convex dorsal surface, I was able 

 to trace in transverse section that a single cell of the hypodermal 

 row, lying laterally but towards the internal side of each lobe of 

 the anther, and containing granular protoplasm and a prominent 

 nucleus, had undergone longitudinal division, parallel to the long 

 axis of the anther. This hypodermal cell in which division occurs 

 constitutes the archesporium of Goebel 8 . The archesporium so 

 divided consists therefore of an inner and an outer segment. The 



1 Zur Entwickclungsgeschichte der Zostera, Bot. Zeitung, 1852, No. 7, pp. 

 121—131, plate iii. 



2 Das Microskop, ii. Aufl. p. 166 et seq. 



3 Grundziige. 



4 Linncca, iv. p. 94, 1829 ; also Trans. Royal Acad, of Sciences, Berlin, Nov. 

 1831. 



5 Linn, Trans., Vol. xvi., p. 717 et seq. 1833. 



6 Ann. des Sci. Naturelles, Ser. i., Vol. xxiv., pp. 263—279, plates 13—14 B. 



7 De Pollinis Orchidearum Goiesi ac Structura, Leipzic, 1852. 



8 Beitrage zur vcrgleichenden Entwickclungsgeschichte der Sporangien. Bot. 

 Zeit. 1881. 



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