Organization in Phcenogamous Plants, 243 



since it becomes subsequently converted into the sac of the 

 embryo. This takes place in all Phanerogamia without ex- 

 ception, and at a period long previous to impregnation ; no 

 more than this, however, constitutes the essence of this- forma- 

 tion. In other respects this sac is subject to the most mani- 

 fold varieties : 1. In relation to form, being sometimes round, 

 sometimes oval, cylindrical, bottle-shaped, or sometimes fiddle- 

 shaped, or, as in Lathrcca squamaria^ where the excavations 

 are shapeless. 2. In relation to the point of the nucleus, which 

 is sometimes nearer, at other times farther off. 3. As to con- 

 tents, at one time clear as water, homogeneous and fluid, at 

 another opake and granular, and sometimes cellular. 4. With 

 respect to the time of its formation, whether a longer or shorter 

 interval before the opening of the flower. And lastly, in the 

 greater or less compression of the nucleus. But a treatise may 

 easily be written concerning the varieties of the embryo-sac 

 previous to impregnation. 



We have now proceeded so far in the process of develop- 

 ment of the plant that we already stand at the door of the 

 sanctum. The process by means of which the new organism 

 should be formed out of the parent plant, remained during a 

 very long time an object of the fantastic sports of the imagi- 

 nation, or of falsely-grounded analogies taken from the animal 

 kingdom, which arose partly from the impossibility of actual 

 observation on account of the imperfection of instruments ; 

 until at length Amici, Brongniart, and R. Brown threw an 

 entirely new light on the matter by their beautiful disco- 

 veries. Yet the most important part of the secret remained 

 undisclosed. I have prosecuted and repeated with untiring 

 zeal the discoveries of those great men, and have not only found 

 the most important of their individual observations confirmed 

 as general laws, but believe that I have advanced a not unim- 

 portant step in the inquiry. I have followed the pollen-tubes 

 (pollenS'Cltlduche) already in so many (upwards of 100) dif- 

 ferent families, with the most patient investigation from the 

 stigma into the ovulum, that there can be no doubt concern- 

 ing this being the general process in all Phanerogamia. R. 

 Brown has described more than one pollen-tube as entering 

 into one micropyle ; I have observed two to three in many 

 plants — in Phcyrmium tcnax three to five, in Lathrcea squa- 

 maria scarcely ever less than three, and once even seven. 



If the pollen-tubes be followed farther into the ovulum, a 

 process perhaps the most delicate that occurs in botanical in- 

 vestigations (fig. 3 and 24), it will be found that usually only 

 one, rarely a greater number*, of the pollen-tubes entering 



• As is the case in thg regular and accidental Pvlycmbrij9nat(ef to the 



2Cg 



