170 Meyen's Report for 1889 on Physiological Botany. 



months before blossoming the cellular tissue of the anthers is 

 uniform, and is divided into small cavities with green sides 

 or walls. These cavities increase, and their cellular contents 

 vanish in order to make room for other cells of large size, 

 which are called " les utricules polliniques " (so-called pri- 

 mitive or mother-cells, Mutterzellen), and for one or two 

 nuclei mixed with an infinite number of very small globules ; 

 the nuclei are the commencement of the pollen-grains ; 

 these '^ utricules " thicken, become opake, and exhibit con- 

 centric, more or less regular, layers in their circumference ; 

 and finally in each tube (Mutterzelle ! M.) there are enclosed 

 four yellowish nuclei, which are more or less rounded, and 

 have in the centre a bright spot. Afterwards, the substance 

 which caused the thickening of the "utricules polUniques" 

 deposits itself between each of the four nuclei which were 

 contained therein, and produces cavities having the form of 

 the nuclei (this is the formation of the special primitive cells, 

 Specialmutterzellen,M.) ; and finally this substance disappears, 

 and the pollen-grains are found lying free in the cavity of 

 the anther. In this matured state they exhibit small papillae 

 on their surface ; and when the nucleus which they previously 

 contained has disappeared, an inner membrane is also to be 

 seen. The anthers of Viscum album do not possess those 

 retiform cells which are seen in so many other plants. 



From the first appearance of the flower, the ovarium, as 

 well as the anthers, coheres with the calyx, and it consists 

 of a green, uniform, cellular mass, in which no cavities 

 are to be distinguished. Some time after the blossoming 

 one observes two small holes, which are formed in the cir- 

 cumference of the ovarium, and in the centre of the cellular 

 tissue. After fertilization these cavities increase, and on 

 their junction they represent the cavity of the endocarpium. 

 In Paris the Misseltoe blossoms in March or April, and the 

 ovulum appears at the end of May or in the beginning of 

 June. About this time it makes its appearance as a pulpy 

 wart, fastened to the base of the endocarpium ; it is gene- 

 rally accompanied by two fine filaments, which are the rudi- 

 ments of two abortive ovula. 



As no ovulum-tunics (eyhiUlen) were observed, M. De- 

 caisue concludes that the ovulum is here in its simplest form, 

 and consists solely of a nucleus ; but from observations I 

 have made, it is evident that the embi'yo-sac, with the con- 

 tained albuminous body and the embryo, were mistaken for 

 the naked ovulum or simple nucleus : the following state- 

 ments are therefore to be corrected ; the proofs of the above 

 will appear hereafter in a research by myself. The report 



