OF THE EMBRYOS IN THE SEEBS OP CONIFER^E. 569 



the extreme slowness in the process of maturation, con- 

 joined with the considerable size of their seeds, and also 

 from the striking peculiarity already noticed, were probably 

 the best adapted for an investigation into the origin and 

 successive changes of the vegetable embryo. 



With this view chiefly I commenced in the present 

 summer (1834) a series of observations, intending to follow 

 them up from the period when the enlargement of the im- 

 pregnated cone begins to take place, to its complete ma- 

 turity at the end of the second or beginning of the third 

 year. 



Pinus sylvestris was selected for this purpose, corres- 

 ponding observations being also made on other species, 

 particularly Pinaster and Strobus ; and although the inves- 

 tigation is necessarily incomplete, the facts already ascer- 

 tained appear to me of sufficient importance to be sub- 

 mitted to physiological botanists. 



In an essay on the organs and mode of fecundation 

 in Orchidece and Asclepiadece, published in 1831, I have 

 given some account of the earliest changes observable in 

 the impregnated ovulum of the former family; and in 

 noticing the jointed thread, or single series of cells by which 

 the embryo is suspended, I remarked that the terminating 

 cell or joint of this thread is probably the original state of 

 what afterwards, from enlargement, subdivision of its 

 cavity, and deposition of granular matter in its cells, 

 becomes the more manifest rudiment of the future embryo. 



I had not indeed actually seen this joint in its supposed 

 earliest state ; the following observations on Pinus, how- 

 ever, will perhaps be considered as giving additional pro- 

 bability to the conjecture. 



But before entering on my account of the origin and de- 

 velopment of the embryo in Pinus, I shall state briefly the 

 still earlier changes consequent to impregnation that take 

 place in this genus ; not only with the view of rendering 

 the account of the embryo itself more readily intelligible, 

 but also in confirmation of the opinion formerly advanced 

 on the nature of the female organ in ConifercB and Cycadea. 



The first and most evident change observable is the pro- 



