Dr. W. Hofmeister on the Fecundation of the Coniferse. 435 



pusculum. It had only just touched the corpusculum immediately 

 adjoining this one, but impregnation had taken place in both. 

 The rarest cases are those in which the pollen-tube sends out a 

 slender, very short pouch between the covering-cells of the cor- 

 pusculum, these at the same time retaining pretty much their 

 original position and form. 



I always found the projecting pouches of the pollen-tubes 

 closed, even in the cases where it was evident impregnation had 

 but just taken place : when the first cell of the pro-embryo, free 

 and of spherical shape, had not yet descended to the bottom of 

 the corpusculum. In Biotia orientalis it is not difficult to pre- 

 pare the pollen-tube free from the albumen, and to extract its 

 perfectly closed projection out of the impregnated corpusculum. 

 In the Junipers this manipulation is rendered difficult, by the 

 rapid expansion of the contents of the corpuscula both in pure 

 water and in solutions of salts or sugar. But the phenomena 

 usually occurring here in the expansion and final bursting of the 

 corpuscula are so much the more convincing ; the pouch of the 

 pollen -tube which had penetrated into the corpusculum is turned 

 inside out, and a rapid whirling current is set up into it. 

 Finally, the vesicular expansion bursts, and the contents of the 

 corpusculum make their way into the interior of the pollen-tube. 



After the arrival of the pollen-tube at the corpusculum, one of 

 the cells which had been produced in its interior increases in 

 circumference and in its finely- granular contents. In none of 

 the Cupressinese did I see this cell in contact with the pouch of 

 the pollen-tube which had penetrated the corpusculum. On the 

 contrary, in many cases the position of its unaltered sister-cells 

 rendered such a process in a high degree improbable, inasmuch 

 as these so filled up the space between that cell and the end of 

 the pollen-tube, that the enlarged cell could not have made its 

 way through them. In the earliest conditions of which I could 

 get a view, the enlarged impregnated cell was in the upper 

 third of the corpusculum; in other cases in its centre or lower 

 end, where it is at first only loosely imbedded. In many in- 

 stances a globular nucleus without nucleoli may be detected in 

 its centre, in other cases this cannot be made visible. The 

 region of the corpusculum below the descending impregnated 

 germinal vesicle, is remarkably poor in cells. 



After the impregnated germinal vesicle has become firmly 

 adherent to the lower end of the corpusculum, it divides, in all 

 cases, by a horizontal septum. Then first, often only in the 

 lower cell of the two, occurs the formation of longitudinal septa, 

 converting the pro-embryo into a body composed of parallel 

 longitudinal rows of cells. 



During this process, those small cells with opake contents 



28* 



