JOUENAL 



OF THE 



ROYAL MICROSCOPICAL SOCIETY. 



OCTOBER, 1912. 



TRANSACTIONS OF THE SOCIETY. 



IX. — Notes on Pollen. 

 By The RroHT Hon. Lord Avebury, P.O. F.R.S. D.C.L. LL.D. 



{Read June 19, 1912.) 

 Plates VII. and VIII. 



At an early stage of development the cells composing the young- 

 anthers form a continuous mass, but the future pollen-sacs soon 

 dissociate themselves from the rest, and the contrast between the 

 contents of the chambers and the surrounding tissue becomes more 

 and more marked. The " archesporial cells," or future pollen-sacs, 



EXPLANATION OF PLATES VII. and VIII. 



Fig. 1. — Represents, after Juranyi, a gerniinatiug pollen of Ceratozamia longifolia. 



X, nucleus ; a, c, d, prothallium ; 6, granular contents of grain ; 



y, three-celled prothallium. 

 „ 2. — Germinating pollen of Ceratozamia longifolia, after Juranyi. e, extine; 



t, pollen-tube arising from the intine ; a, c, d, prothalliimi. The figure 



also shows numerous starch (s) granules and two nuclei. 

 „ 3. — Centaurea Cyanus Linn. Upper part of style. x 20. AC, apex of 



anther-cylinder ; BH, brush of hairs that pushes the pollen out of the 



anther-cylinder ; SA, side view of style-arms. 

 „ 4. — Ditto. Style-arm, showing the inner or stigmatic surface, x 40. 

 „ 5. — Salix pcntandra Linn. Style and stigmas. x 40. S, the style ; AA, 



the arras of the stigmas ; LSt, LSt, LSt, LSt, the four lobes of the 



two stigmas. 

 ,, 6. — Ditto One lobe of a stigma, x 80. PPPPP, grains of foreign pollen, 



probably that of the Daisy and Dandelion. 

 ,, 7. — Ranunculus Ficaria Linn, x 400. Three spherical poUen grains, newly 



taken from anther 

 ,, 8. — Ditto. The same three after 15-20 minutes' exposure to a dry 



atmosphere. 

 ,, 9. — Ditto. End view of another pollen. 

 „ 10. — Section of pollen of Poinciana pulcherrima, after Schacht. X 800. 



[Fig. 11 



Odoler 16th, 19m 2 k 



