Fertilization in Phanerogams 177 



company it, do not play any role in the true process of 

 fertilization. 



Everybody is acquainted with the valuable investiga- 

 tions of Strasburger in this field which, since 1878, have 

 repeatedly treated this point and have completely proven 

 the above mentioned theories. It would be superfluous 

 to redescribe them here, or to enumerate their confirma- 

 tions by other investigators. 



How the nuclei unite during fertilization is a question 

 which is very far from haying been satisfactorily an- 

 swered. Furthermore, differences predominate here 

 which are at least very striking. According to Stras- 

 burger, not only do the nuclear skeins fuse, but also the 

 nuclear vacuoles, and hence the nuclear sap. 18 Accord- 

 ing to van Beneden, the nuclear skeins of the male 

 and the female cells in Ascaris megalocephala arrange 

 themselves side by side and form the segmentation nu- 

 cleus. 19 They seem to unite at their ends, thus forming a 

 single nuclear thread, in which, therefore, only juxtapo- 

 sition takes place, and not a mutual penetration of their 

 elements. But while, in animals, according to the avail- 

 able data, fusion does take place during the state when 

 the chromosomes are arranged in the form of a star, it is 

 seen to occur in the plants in the state of rest. Whether 

 this difference really exists, and how the nuclear threads 

 generally unite, are questions which have to be more 

 thoroughly investigated. 20 



It is significant that the number of the chromosomes, 

 according to Strasburger's most recent investigations, has 



l8 Strasburger. Ueber Kern- und Zelltheilung, p. 230. Jena. 



19 Van Beneden, E. Recherches sur la maturation de I' oeuf. 

 1883. 



29 Strasburger. Ueber Kern- und Zelltheilung. p. 240. Jena. 1888. 



