Chap, hi The Morphology of the Flower 109 



from the zygote, but from the suspensor instead of the 

 normal segment. 



A case in which an embryo of very doubtful morpho- 

 logical value occurs was described in 1898 by Treub, and 

 in 1899 by Lotsy. This is the genus Balanophora. Fertili- 

 zation does not occur ; the embryo is formed by the upper 

 polar nucleus, a case presumably of parthenogenesis, if 

 we recognize this nucleus as sexual and the sister nucleus 

 of that of the oosphere. But in addition both observers 

 found that a cell in the midst of the endosperm started the 

 formation of a second embryo, though it did not develop 

 very far. 



True parthenogenesis, the development of the oosphere 

 into an embryo without any sexual fusion, was observed by 

 Juel in 1898 in Antennaria alfiina. He noted further that 

 its chromosomes do not vary from the haploid to the 

 diploid condition, but are constant during the whole of 

 the life-history of the plant, and that no divisions of the 

 heterotypic kind occur. Just at the close of the century 

 Murbeck observed almost exactly the same phenomena 

 in several species of Alchemilla. 



