222 THE CONTINUITY OF THE GERM-PLASM AS THE 



the cell-body, but we must remember that it has ben hitherto a 

 question whether the head of the spermatozoon is formed from the 

 nucleus of the cell or from the paranucleus ; and that the observers 

 who held the former view were in consequence obliged to regard 

 the paranucleus as a product of the cell-body. But according- to 

 the most recent investigations of Fol 1 , Roule 2 , Balbiani 3 , and Will 4 , 

 upon the formation of the follicular epithelium in the ovary of 

 different groups, it is not improbable that parts of the nucleus 

 may become detached without passing through the process of 

 karyokinesis. Thus it is very possible that the paranucleus may 

 be a product of the main nucleus and not a condensed part of 

 the cell-body. This view is supported by its behaviour with stain- 

 ing reagents, while the other view, that it arises from the cell- 

 substance, is not based upon direct observation. Consequently 

 future investigation must decide whether the paranucleus is to 

 be considered as the spermogenetic nucleoplasm expelled from the 

 nucleus. But even if this question is answered in the affirmative, 

 we should still have to explain why this nuclear substance, remain- 

 ing in the cell-body, does not continue to exercise any control over 

 the latter. 



Strasburger has recently enumerated a large number of cases 

 from different groups of plants, in which the maturation of both 

 male and female germ-cells is accompanied by phenomena similar 

 to the expulsion of polar bodies. In this respect the phenomena 

 occurring in the pollen-grains of Phanerogams bear an aston- 

 ishing resemblance to the maturation of the animal egg. For 

 instance, in the larch, the sperm-mother-cell divides three times 

 in succession, the products of division being very unequal on each 

 occasion ; and exactly as in the case of polar bodies, the three small 

 so-called vegetative cells shrink rapidly after separation, and have 

 no further physiological value. According to Strasburger, the so- 

 called 'ventral canal-cell,' which, in mosses, ferns, and Conifers, 



1 Fol, ' Sur 1'origine des cellules du follicule et de 1'ovule chez les Ascidies.' 

 Compt. rend., 28 mai, 1883. 



2 Roule, 'La structure de 1'ovaire et la formation des ceufs chez les Phallusiadees.' 

 Ibid., 9 avril, 1883. 



- 3 Balbiani, ' Sur 1'origine des cellules du follicule et du noyau vitellin de 1'oeuf 

 chez les Geophiles.' Zool. Anzeiger, 1883, Nos. 155, 156. 



4 Will, ' Ueber die Entstehung des Betters und der Epithelzellen bei den Aniphi- 

 bien und Insecten.' Ibid., 1884, Nos. 167, 168. 



