REVIEWS. 415 



Further, that organised bodies must be looked upon as 

 constructed of extremely complex networks of molecular 

 chains, nets, &c. Undoubtedly the discussion of this part 

 of the subject is interesting, even fascinating, but we cannot 

 avoid pointing out the danger of building general hypotheses 

 on a foundation of considerations which are themselves so 

 extremely hypotbetical. This danger is, of course, clear to 

 the distinguished author; but perhaps all his readers will 

 not bear in mind that his object in publishing such specula- 

 tions is rather to stimulate further work than to offer a solu- 

 tion of these great and difficult questions. We have by no 

 means got to the bottom of the more immediate structure 

 of organised structures : to go further and discuss their 

 ultimate structure is, indeed, a work requiring careful 

 treatment. 



Strasburger's speculations are not confined to this subject 

 however ; he proceeds to an excellent criticism of recent 

 views on the " Assimilation of carbohydrates," to which we 

 cannot here do justice, and then concludes with speculations 

 concerning the " Role of the cell nucleus," " The penetra- 

 bility of the cell wall," and '' The behaviour of the cell nu- 

 cleus in fertilisation." 



We have already referred to the idea that in Angiosperms 

 the substance of the nuclei in the pollen grain becomes dis- 

 tributed, and after passage into the egg again aggregated. 

 In cases where a single pollen tube is formed the nucleus 

 can be traced to near the end, preserving its nuclear sub- 

 stance in this form till the last moments before passage over 

 to the egg ; in Gymnosperms it does not thus disappear, 

 but may even multiply. That the nucleus can suifer " frag- 

 mentation" is proved by what occurs in Cliara foetida, »&c. 



Strasburger withdraws his earlier statement, that the cell- 

 nucleus in the mother-cells of spermatozoids in Ferns falls 

 to pieces. As Schmitz says, the nucleus here enlarges until 

 it has gathered all the protoplasm to itself, a process agree- 

 ing with what Fleming finds in the case of animals. 



In higher organisms the male element becomes more and 

 more reduced till little more than the nucleus remains, 

 the tail of the spermatozoid perhaps being cell-plasma. 

 Here, then, is some support for the view that the nucleus is 

 the proteid former, or, at any rate, plays an important part 

 in the formation of the basis of life. 



It is interesting to note that in Spirogxjra, where the 

 nucleus was believed to disappear in copulation, Schmitz 

 finds by reagents that it is in substance still there. 



As to the role of the cell nucleus, Strasburger considers 



