£26 Inquiry into the Structure of Seeds. 



presently endeavour to show ; but I must first speak of the 

 more immediate object of the present essay. 



Gaertner asserts the vitellus of seeds to be <c distinct from 

 the cotyledons as well as from the albumen, and, for the 

 most part, situated between the latter and the embryo." 

 He considers as its principal diagnostics the three following 

 characters : " 1st, That it is most closely connected with the 

 embryo, So as not to be separable from it without injury to 

 its own substance : 2dly,That notwithstanding this intimate 

 connection, ir never rises out of the integuments of the seed, 

 as the cotyledons usually do, in germination, so as to be- 

 come a seminal leaf, but, rather like the albumen, its whole 

 substance is destroyed by the seedling plant, and converted 

 into its own nourishment : and 3dly, That if the albumen 

 be likewise present, the vitellus is always situated betwixt 

 that and the embryo, in such a manner, however, that it 

 may be separated from the albumen with great ease and 

 without injury." For which reasons this able writer con- 

 siders the organ in question as " allied on the one hand to 

 the albumen, on the other to the cotyledons," but truly 

 distinct in nature from both. He proceeds to observe that 

 " it is of all the internal parts of a seed the most singular, 

 and by far the most unfrequent." 



Now, to consider all these points separately, in the 1st 

 place, The vitellus is not more closely connected with the 

 embryo than the greater part of cotyledons are; according 

 to the figures and descriptions of Gaertner himself, the fi- 

 delity of which must be evident to any one in the habit of 

 using his book, and especially to those who will take the 

 trouble of comparing a few of them with the seeds to which 

 they refer, while in the earliest stage of germination, at 

 which time the relative connection of the parts is best ascer- 

 tained. 2dly, That the vitellus never rises out of the ground, 

 is a circumstance common to it with many cotyledons, al- 

 lowed to be auch by Gaertner, as in the leguminous plants, 

 and others already mentioned. 3dly, That the vitellus is 

 situated between the albumen (if the latter be present as 

 a separate organ) and the gmbryo, is only a necessary con- 

 sequence 



