STRUCTURE OF SEED. 187 



gether do not seem to make more than one, and the 

 embryos of which are developed simultaneously. What- 

 ever be the cause, this plurality of embryos does exist 

 in some seeds, and they are sometimes isolated from one 

 another, and at other times united together. This last 

 case has been observed by my son : having remarked a 

 plant of Euphorbia Helioscopia, (PL 22, fig. 1,) which 

 came up with four cotyledons, he perceived that this 

 number was owing to there being two embryos united 

 together throughout their whole length; he has since 

 observed in Lepidium sativum, and Sinapis ramosa, this 

 same monstrosity, which bears the same relation among 

 plants to the monstrous animals formed by the union of 

 two young ones. We know that in these animal mon- 

 strosities, it frequently happens that a part of the organs 

 of one or both of them disappears ; it is in this way that 

 calves with two heads, or six legs, &c, are formed. 

 The same happens in the union of embryos ; some 

 instead of four cotyledons, have but three ; this is what 

 is observed in the Euphorbia and Lepidium of which 

 I have spoken, and in Ranunculus, Solanum, the Bean, 

 &c. &c. In order to complete what relates to the plu- 

 rality of embryos, I have slightly deviated from the 

 natural order of facts, to which I now return. 



The seeds of the same plant are not all exactly of the 

 same size ; in most cases this difference is of little im- 

 portance, and we generally select the largest seeds for 

 sowing, because it is remarked that the plants proceed- 

 ing from them are more vigorous. But in some cases 

 this difference of size has a peculiar interest ; thus, 

 M. Autenrieth has remarked that among the seeds of 

 the Hemp, which is a plant constantly dioecious, the 

 longest, largest, and heaviest, produce male plants, whilst 

 those which are rounder and less heavy, produce female 

 ones ; the former have a longer radicle, and germinate 



