Dr. Balfour on the Fertilization of Plants. 48 



8M March, 1842,— 7%« Presidbnt in the Chair. 



Charles T. Dunlop, Esq. elected a member. 



The Committee on Publication, appointed at last meeting, gave in 

 a report recommending the publication of the Proceedings. The 

 report was ordered to lie on the table till next meeting. 



The following communications were then made. 



XII. — On the Fertilization of Plants, By Dr. Balfour, Regius 

 Professor of Botany , in the University of Glasgow, 



Dr. Balfour, in the first place, described shortly the organs of 

 plants which are concerned in fertilization, and alluded more particu- 

 larly to the structure of the pollen. He showed the various provisions 

 made for protecting the pollen, and for allowing it to bo applied to 

 the stigma, and illustrated these in the case of Orchidea, Asclepiadece, 

 Vallisneriaf StratioteSf Hottonia, Zostera, Aristolochia, Slylidiuniy Parie- 

 tariuy Berberis, Urticay Cornus canadensis, Ficus, «fec. 



He next alluded to the boat developed at the time of fertilization, 

 the absorption of oxygen, the formation of carbonic acid, and the con- 

 version of starch into sugar. The experiments of Brongniart and 

 of Vrolik and Do Vrieso on Colocasia odora were detailed. 



The structure of the anther, more especially its inenchyma or 

 elastic fibro-cellular coat, and the discharge of the pollen were next 

 considered, and observations were made on the fluid covering the 

 stigma, which by Aldridge is said to be acid, and by Vaucher is 

 looked upon as the nectariferous fluid secreted by glands on the petals. 



Dr. Balfour then explained the changes produced in the pollen 

 grain when it came into contact with the stigma, the production of the 

 pollen tube, and descent of the fovilla. 



Various theories, ho stated, have been brought forward relative to 

 the fertilization of plants. 



Schleiden and Wydler conceive that the pollen tube enters the 

 foramen of the ovule, and that its extremity becomes the embryo, a 

 theory supported by Dr. Giraud, who thinks that the position of the 

 embryo seems to indicate that it is a foreign body introduced into the 

 ovule from the outside. 



Dr. Carpenter thinks that it is not the pollen tube, but one of the 

 pollen granules which becomes the embryo, and he traces an analogy 

 between this process and what takes place in the lowest algae as the 

 Protococcus, &c. 



Mirbel and Spach oppose Schleiden's views, and think that he has 

 mistaken what they call the primary utricle for the end of the pollen 

 tube. They maintain that this primary utricle exists before impreg- 

 nation, or before the pollen tube is protruded; and tliat after the 

 influence of the pollen is conveyed to it, the embryo becomes devel- 

 oped. Their experiments were made on the Zea Mays. 



