488 Dr. W. Hofmeister on the Fecundation of the Coniferse. 



Transverse diameter of the mouth of the corpusculum into 

 which a short protrusion of the poll en-tube had penetrated, 

 0-111 millim. 



b. Smallest diameter of a cell-rosette adherent to the lateral 



wall of the pollen-tube, 0*500 millim. 



Greatest diameter of the same, 1*225 millim. 



Transverse diameter of the mouth of a corpusculum impreg- 

 nated by the same pollen-tube, 0*124 millim. 



Transverse diameter of the unicellular rudiment of a pro-; 

 embryo situated at the bottom of the same corpusculum,'^ 

 0*832 millim. ^i 



c. Transverse diameter of the orifice of a pollen-tube torn off* 



at the point of entrance into the corpusculum, 0*013^^, 

 millim. ^^ 



Upper end of the eight-celled pro-embryo situated at the-^ 

 bottom of this corpusculum j 0*861 millim. 



2. In a pollen-tube dissected free from an impregnated cor- 

 pusculum, I detected the shrivelled remains of the cell-rosette 

 contained in it, situated above the point where the latter had 

 been torn off. 



3. The upper part of the corpusculum, not filled up by the 

 pro-embryo, eontained free cells exactly similar to those existing 

 there before impregnation. ;, 



4. There is no reason to doubt that the simple cells, fre- . 

 quently observed, filling up the lower concavity of the corpus- . 

 cula of Taccus baccata and canadensis, are the primary cells of 

 the pro- embryos. But, in that case, they could not derive their 

 origin from the cell-rosettes contained in the pollen-tube. 



I owe to the kindness of my friend Schacht, a sight of his 

 preparations of Taxus baccata. They have not been sufficient 

 to convince me of the correctness of his interpretation. Schacht 

 has several times observed that in Taxus also (as frequently 

 happens in Juniperus and the Abietinece) the pollen-tube pene- 

 trates pretty deeply into the corpusculum and there expands to 

 a certain extent ; — perhaps an individual peculiarity of the spe- 

 cimens which furnished Schacht with the materials for his 

 investigations ; throughout very numerous examinations I have 

 never met with anything of the kind. These vesicularly-ex- 

 panded pouches of the pollen-tube, separated from the corpuscles, 

 were of very various magnitudes. I estimated the diameter of 

 one at 0*1 millim.; of another at 0*4 millim. The largest 

 would therefore have about half filled a corpusculum ; a condition 

 which is sometimes at least approximatively attained even in the 

 gigantic corpuscula of the Abietinea. The but indistinctly 

 perceptible cellular structures existing in these protruded sacs 



