Plants, and Parthenogenesis. 93 



only three flowering plants of C. itidfolia existed in the Berlin 

 Botanical Garden, and two of the self-same examined by him 

 I also had the opportunity of investigating. 



Thus it appears that the last insecure prop to the hypothesis of 

 parthenogenesis in plants is thrust aside, and it is established 

 beyond doubt that the production of a normal germ in the 

 female organs is dependent upon the cooperation of the male 

 organs of plants. 



The Pollen. 



The pollen escaped from the anthers of Ccelebogyne is sphe- 

 rical, and composed of a Very delicate smooth integument en- 

 closing fluid contents. The external coat is remarkable in having 

 three symmetrically-disposed darker or clearer specks on its 

 surface. The fluid contents have suspended in them a multitude 

 of oval and rounded firm coq)uscles, which are coloured partly 

 blue and partly yellow by iodine. 



The different transparency of the three points alluded to in 

 the wall of the pollen is due either to the presence of small 

 globular (collenchymatous) corpuscles, or to the detachment of 

 such cells, and the consequent production, by the spaces left in 

 the coat where they adhered, of clear circular specks with a dark 

 outline. The internal very dehcate pollen-coat, which cannot be 

 distinguished from the outer tunic except after the application of 

 chemical reagents, becomes evident at these clear spaces when the 

 pollen-cell proceeds to elongate itself on the stigma (PI. X.). 



The pollen-grains (united in groups of four) contained within 

 the half-developed anther-cell possess thicker coats, and on that 

 account completely occupy the mother-cells in the parenchyma, 

 of which four are formed in each anther-cell. The special mother- 

 cells are very manifest, and are thickened during the whole period 

 of the deliquescence of their parent-cell, and present the appear- 

 ance of "imperfect" parenchyma-cells (collenchyma) (PI. X.). 



These cells enclose four others of a second generation, one of 

 which, the intine of the future pollen-grain, at this period 

 almost entirely fills up the parent-cell, and contains a uniformly 

 thick mucoid fluid, whilst the other three grow to a very trifling 

 extent, and are so compressed by their largely-developed fellow- 

 corpuscle against the wall of the mother-cell, that they come to 

 occupy a position between the two coats of the pollen-cell — the 

 extine and the intine. 



They are the " intermediate corpuscles," described by Fritsche 

 as having a similar situation in the cell-structure of all varieties 

 of pollen, and without doubt owe their origin to the same cause 

 which gives rise to the circumstance that the vesicles* which cha- 



* I frequently call the non-nucleated cells, which commonly perform a 

 secretory function (H. Karsten, De Cella Vitali, 1843, p. 64), for brevity's 



