MAI 01 mi I :<.. AM* PROCESS OF FERTILISATION. 37 



tin- egg were ei. 



: we inijuiiv after its physiological meaning. 

 rminative \esiclc in. mctam<irph"-is into com p 



tally comprehensible, for a firm membrane and a iieh m 



of nucIeoplaMii certainly cannot be neees-ary to the int.-:. protoplasm 



and acthe nuclear siil-tance in the pn>ce>-es of division. Itsdissoluti 



Were, tin- preliminary reijiiii vm nt \r tin- reiie\ve| aetiv; 1 iclear 



lit-. I'.ut what function shall one a-cribe to tin- polar cells? 

 ; !hi- -M '\eral h\p"lh>-- > have l.een j,n.].. 



BALVOUB, I><;WICK MIVT. \ \N I:IAI I.I.N. and otben, in ol pinion 



that tlie iniinature i-^ir, like e\ery ..tlier cell, is ..ri.u'iually hernia|'h: 



tliat l>y the iie\-e!..piiient of polar cells it ri!s i 1 male cin>titu 



Its nnoleoB, which afterwards are ivpiaeeii \ t \- fertilisation. r..\i.r- 



that, if no polar cell> were forme 1, part lieno_u f eiie>i- mu>t normally occur. 



\V 1.1 -MANN, >upported by his discovery in the case of eggs developing 

 parthem 'genetically (p. 34), ascribes a different function to the lir>t ai 

 second polar cells, lie di-tiniruishes in the <:enninative vesicle two different 

 kinds of plasma, which he designates ovogenetic and germinal \i].. 

 He maintains that by the formation of the !h>t polar cell the uvo-, 

 plasma is eliminated from the ovum; by that of the second polar cell, half 

 of the LTerminal plasma. In the latter case the ejected germinal plasma nut-t 

 be replace 1 by fertilisation. 



Thes;.' hypotheses appear to me upon closer examination t. present many 

 vulnerable points. To me appears more promising an interpretation of 



- in.i, who comi ares the egg, as had already often been dt< 

 mother-cell of spermatozoa. Just as the latter gives rise to many spermatozoa, 

 so also the eirs? must have once possessed the capability of di\ : .:' into 



eggs. Jn the formation of the polar cells, which are eggs that 

 become rudimentary, as it were, there has been p: of these 



al cnnditi' l'.'>vi:i:i regards the polar cells as ulmrtivt} 



1 have likewise always conceived of the conditions in this manner. 



2. The Process of Fertilisation. 



The union of egg-cell and spermatic cell is dY-iirnated as t lie process 



of fertilisation. This process is to bo ol.xTvt <!, M>mrtime> with i^u-.tt 



ulty, sometimes with con>i(lrraMc ease, ncronling to the choice of 



tlu- annual for t'.\}>rriiUL']itati<>u. The invotiiratnr 'nlinaril\ 

 c"unter.> rivat difficulties in caso^lu-re tlie rij re nt lail. lut 



where a part, if not the wiifle. of their development is rHi-c! '1 within 

 tin- sexual ducts of the maternal organism. In Mich ca>e> the fertili- 

 sation also inuM ( videiitly take place in thoduct>of t lie female sexual 

 apparatus, into which the semen is introduced in the act of 



copulation, 



An inl- r,"il /> rtili^it'c-ii takes place in nearly all VerteLi 

 except tin- greater part of the KM n -sain I many Amphibia. Usually t he- 

 aid the spermatozoa meet, in the case of Man and Mamma 



