138 GENERATION. 



is the first formation in the process of generation ; but 

 the origin of which is to be looked for in the material or 

 dynamic influence of the pollen-tube, (the development 

 taking place in the interior of the ovule, and within the 

 sac of the embryo, ) and by no pressing in of its membrane. 



236. After a little time this bladder is extended in the 

 form of a thread, or suspensor, as it is by some termed, 

 having a larger and swollen cell tit its lower end, and 

 then, and not before, is the future embryo to be seen 

 within this swollen end of the suspensor. 



237. In those cases, in which the nucleus already 

 exists as a hollow case, the plastic process is a little dif- 

 ferent, the pollen-tube having entered the ovule by the 

 foramen, pierces the end of the nucleus as before, but 

 descends at once into the interior of it, at the end of 

 which, after a certain change, the little bladder is formed, 

 and which presents the same modifications as mentioned 

 before, in regard to the suspensor and embryo. 



238. In no case whatever is the young embryo to be 

 looked upon as produced directly by the end of the 

 pollen-tube, and therefore a product, originally of the 

 stamen ; but as arising within the nucleus, on account 

 of certain influences conveyed there by the pollen-tube, 

 and, therefore, is a. product of the pistil. 



239. The difficulty of knowing what takes place at 

 the union of the end of the pollen-tube with the upper 

 end of the embryo sac, can only be met by the igno- 

 rance we are in of a somewhat analagous process in the 

 animal body. 



Second Division. 



240. Without stopping to notice the opinions of Spal- 

 lanzani, Smellie, and some others, who have denied the 

 existence of sexes in Plants, we shall state the views 

 of some eminent living German botanists, upon the 

 subject of generation, and which at the present mo- 



