688 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



tions : — The fertilizing tubes come into contact with every oosphere 

 in the polysporous oogonia, accompanied by the obvious disappearance 

 of a portion of the contents of the tube. Protoplasmic structures, 

 which can be proved to belong to these contents, are often subse- 

 quently found free in the oogonia in addition to the oospores. These 

 processes correspond exactly in time with the transformation of 

 Gospheres into oospores. In Pythium the passage of the contents of 

 the tubes into the oospheres can be directly observed. In Achlya 

 polyandra, not only does this contact of the fertilizing tube take place 

 with a definite spot of the oosphere, but the latter is produced into 

 a papilla. Although, undoubtedly, true parthenogenesis occurs in 

 Achlya, Pringsheim believes that de Bary's statement that in the 

 sexual forms reproduction takes place by a kind of apogamy is 

 founded in error. 



Schizomycetes.* — W. Zopf gives an exhaustive account of the 

 Schizomycetes as a contribution to Schenk's 'Encyklopaedie der Natur- 

 wdssenschaften.' The chief point brought forward, in opposition to 

 the older view of this class of organisms, is the genetic connection 

 between the various forms hitherto considered distinct by Cohn and 

 others. The coccus-form (micrococcus) may under certain conditions 

 develope into the shorter (bacterium) or longer (bacillus) rod-form; and 

 if these divide continually, remaining side by side, we get the filiform 

 (leptothrix) form, which again may bend (vibrio) or coil spirally 

 (spii'illum, spirochfete). Continual division of any of these forms 

 again produces the micrococcus, which may bo regarded as the final 

 product, of the nature of gonidia. These different conditions may 

 even be displayed in different parts of the same filament, though this 

 is not usual. No true branching ever takes place, nor any differentia- 

 tion of the cells into vegetative and sterile, as in the Schizophyceae. 

 In the most highly developed forms, as Crenothriz, Beggiaioa, and 

 Cladothrix, a distinction of base and apex may be made out. The 

 mode of vegetative reproduction is always by bij)artition, which may 

 take place in two, or even in three directions, though usually only in 

 one. The cells are always inclosed in a cell-wall, composed, in the 

 bacteria which accompany putrefaction, of a peculiar proteinaceous 

 substance, mycoprotein, in the others of cellulose. The cell-contents 

 consists of a homogeneous protoplasm, mainly mycoprotein, together 

 with oil (the so-called granules). There is no nucleus. Other sub- 

 stances are occasionally also present. Under certain conditions of 

 nutriment all the forms except the filiform become provided with cilia 

 as organs of locomotion. They are apparently contractile threads of 

 protoplasm which project through an opening in the membrane, and 

 can be again withdrawn. Besides the motion imparted by them, they 

 have another oscillatory movement. 



Besides division by bipartition, the Schizomycetes are reproduced 

 by spores. The contents of the cell contract into the smallest pos- 

 sible space, become very dense, and encyst themselves with a thick, 



* Zopf, W., 'Die Spaltpilze. Encyklop. der Naturwies.,' Abth. i., Lief. 32; 

 97 pp., Breelau, 1883. 



