426 Bibliographical Notice. 



whole of the chromatin of the nucleus has become distributed 

 in the plasma. I have acquired a continuous series of develop- 

 mental stages right up to the complete dispersion of the 

 chromatin. Later on one finds the cavity of the skeleton 

 filled with numerous multinucleate globules. It is evident 

 that the process leads to the formation of swarm-spores. 



Again, other individuals are sometimes met with in which 

 in place of the nucleus there is found a vesicle with a con- 

 siderably thickened wall that takes a deep stain with hsema- 

 toxylin or carmine. Tliis wall is clothed on the inside with 

 a coat of protoplasm. The most striking feature in these 

 stages consists, however, in the presence of many larger and 

 smaller globules, which, on being treated with osmium or 

 mixtures containing osn:ium, become black, and seem to con- 

 sist essentially of fat. They lie arranged in a hollow cup 

 (" Kugelschale "^ against the inner wall. In other cases we 

 meet with similar structures outside the nucleus in the endo- 

 plasm. Sometimes there are only one or two such vesicles, 

 at other times a larger number, even amounting to as many 

 as twelve or more. On their appeal ance the nucleus under- 

 goes certain changes — indeed, it may even entirely cease to 

 exist as such ; in the endoplasm, too, degenerative phenomena 

 take place. 



Since it was no part of my plan, in framing the foregoing 

 remarks, to propound far-reaching conclusions and com- 

 parisons, I have confined myself to putting together in simple 

 form the most essential observations. In so doing I have 

 touched very briefly even upon the most important points. 

 My detailed paper, which will appear shortly, contains all 

 further particulars. 



BIBLIOGRAPHICAL NOTICE. 



The CoJlector^s Manual of British Land and Freshwater Shells. By 

 Lionel Eenest Adams, B.A. Second Edition. 8vo. Leeds, 1896. 



A NEW edition of this work will probably be welcomed by manj'- 

 collectors of British land and freshwater shells, as it contains instruc- 

 tions with regard to collecting, the means to be employed, the 

 localities to be searched, the methods of preparing specimens tor the 

 cabinet, and remarks upon labelling, mounting, and arrangement of 

 collections, which may be useful to them. By the more scientific 

 student, however, the book will be less appreciated, as some portions 

 of the classification adopted are very archaic, and mistakes have 

 crept in, so that a want of thoroughness seems to pervade the 



