7o6 THE AMERICAN NATURALIST. [Vol. XXXIX. 



Several papers have appeared on the structure of the yeast 

 cell since Wager's account of 1898. Marpmann (:02) and 

 Feinberg (: 02) described much simpler conditions than are 

 reported by Wager, and recognize scarcely more than a deeply 

 staining body which they term a nucleus. Hirschbruch (: 02) 

 gives an extraordinary description, accompanied by diagram- 

 matic figures, of a nuclear structure and a body, staining red 

 and blue respectively, which are supposed to fuse previous to 

 the development of a bud, but the account is so unsatisfactory 

 as to merit little attention. Janssens (:03) reviews the work of 

 these investigators and others in comparison with his earlier 

 results (Janssens and Leblanc, '98). Guilliermond (:04) has 

 published the most recent paper presenting more completely his 

 conclusions of an earlier investigation in 1902. 



Guilliermond's conclusions have some points of resemblance 

 to those of Wager. He finds, a nuclear vacuole containing a 

 granular network believed to be chromatiQ and a nucleolar 

 structure. The entire body seems to be a true nucleus, not dif- 

 fering in its essentials from the nuclei of other ' fungi. Some- 

 times all the material in the nucleus seems to be condensed into 

 a central body, a sort of chromatin nucleolus (chromoblast) 

 somewhat resembling a similar structure in Spirogyra. Guillier- 

 mond figures the nucleus as constricting during the process of 

 budding, one part passing into the daughter cell. His figures 

 show clearly deeply stained material outside of the nuclear 

 membrane in a position' similar to that of Wager's nucleolar 

 body (nucleolus). 



These points of agreement seem to justify at least in part 

 Wager's account, but of course the peculiarities of both lead 

 one to suspect that there are important features in the structure 

 of the nucleus and in the events of nuclear division which have 

 not been determined. It certainly seems probable that chroma- 

 tin is present in definitely organized bodies (chromosomes) some- 

 times within a vacuole and sometimes lying around a nucleolar 

 structure. The latter also holds an intimate relation to the 

 chromatin, which is frequently true in higher plants. There are 

 indications that a simple type of spindle is present at least in 

 the nuclear divisions during spore formation. In view of 



