Autonomy of the Limiting Membrane 165 



oospores are formed in such a way that each takes up in 

 itself a part of the maternal membrane. 80 



We meet with a greater difficulty in the ascospores. 

 But their origin has not been carefully studied in late 

 years. Thus, though we know that divisions of the 

 mother-nucleus always precede their formation, the ques- 

 tion as to how they acquire their other organs has not 

 yet been studied. It is clear that every spore must get one 

 or more vacuoles through the division of the maternal 

 sap-vesticles, but how this comes about, nobody has yet 

 investigated. The consideration of the other question 

 also as to whence the spores obtain their plasmatic mem- 

 brane, must be most urgently recommended. 



In the same way the origination of the egg-cell in the 

 oogonium of the Peronosporales awaits study by means 

 of modern methods. In this case, too, nothing definite 

 can be said for the present in regard to the origination 

 of the plasmatic membrane. Concerning the membrane 

 of the spermatozoids, consult the following Section (pp. 

 174-176). 



As a final result of this review, we may therefore say 

 that, in all cases in which the arising of a new plasmatic 

 membrane is supposed to take place without contact with 

 the old one, this assumption is chiefly due to investigation 

 by the older and imperfect methods. Exceptions to the 

 rule are not at all known with certainty, although, accord- 

 ing to the hypothesis of intracellular pangenesis, they 

 must not be considered, a priori, as impossible. 



8 De Bary. Abh. Senckenb. Naturf, Ges. 12: 261, 1881. 



