146 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. lv. 



statement refers to the conjugation of the two primordial 

 cells, the last stage of which is the mysterious fusion of 

 nuclei. I believe the micropylar half of the embryo-sac to 

 correspond to four female spores or macrospores, and the 

 antipodal half to correspond to four male spores or micro- 

 spores. The facts which lead me to this belief are the fol- 

 lowing : — The egg-cell in the micropylar region receives the 

 contents of the pollen-tube and develops into the embryo ; 

 it is therefore a true female cell, and its sister-cell I would 

 expect to be also a female cell, and I find that the nucleus 

 of the antipodal cell travels towards the nucleus of the 

 primordial micropylar cell, and that in Myosurus the two 

 nuclei meet in the micropylar half of the sac. The same 

 phenomenon holds good for a great number of plants, although 

 according to Strasburger in other cases the two nuclei approach 

 one another mutually. But not only does, in Myosurus, the 

 antipodal nucleus travel towards the micropylar one, but also 

 the antipodal nucleolus goes to meet the micropylar one. 



Let us shortly study how the conjugation of nuclei is 

 brouo-ht about. " The two nuclei meet in the anterior half of 

 the embryo-sac and become flattened oh' against one another, 

 being themselves evidently quite indifferent. Gradually the 

 two nuclear membranes lying in close contact with one 

 another are dissolved from within outwards, and thus a 

 passage is made for the transit of the antipodal nucleolus 

 into the micropylar nucleus. Tlie two nucleoli come in 

 contact with one another in the micropylar half of the secon- 

 dary, or, as I shall call it, the endosperm-nucleus, and after 

 the formation of a very short bridge-like middle piece the 

 contents of the antipodal nucleolus flow into the micropylar 

 nucleolus. After tlie fusion is completed, a baglike structure 

 is seen in the antipodal half of the endosperm-nucleus, which 

 I interpret as tlie nucleolar bag of the antipodal nucleolus. 

 At the time when the two nuclei liave just come in contact 

 with one another, two, rarely three, very minute granules 

 surrounded by a pale area and reminding me of polar bodies 

 are found constantly in cacli nucleus ; in some cases these 

 bodies seem even to have tlie power of division after the 

 formation of the endosperm-nucleus. 



I shall brielly state some of tlu; changes 1 observed in the 

 newly-formed nucleolus of the endosperm-nucleus ; but I am 



