420 SUMMARY OF CQRRENT RESEARCHES RELATING TO 



The nucleus and nucleolus are situated in the middle of the anterior part 

 of the body. 



The differences from the above genera are exhibited in the following 

 table : — 



1A11 three active Callodictyon. 



Two active, one training Trichomonas. 



( Animal free or fixed Dallingeria. 



One active Animal always free, and without undu-'» Ehirea 



two tiaini'ng , ^^^^'f membrane . . . . . . f (nov. gen.) 



° j Annual tree, but with undulatmg mem-\ ^ . 



\ braue / JrunasUx. 



The author considers that of these Callodictyon is the lowest, and 

 that a gradual differentiation can be traced through the other forms to 

 Elviria, which is always free ; and this is more perfect than Trimastix, 

 since the latter possesses a membrane. The third parasite dealt with is 

 also probably new to science, but the author leaves it undetermined at 

 present, since only one specimen was noted. This is a Ciliate lufusorian, 

 elongated, attenuated in front, enlarged behind. It is transparent, highly 

 retracting, and slightly granular ; there are four or five non-contractile 

 vacuoles in centre, and three in posterior of body. Nucleus anteriorly. 

 The sides, and posterior parts of body are deprived of cilia, and these 

 are very short ; anteriorly the cilia are strong and stout. 



BOTANY. 



A. GENERAL, including the Anatomy and Physiology 



of the Phanerogamia. 



o. Anatomy.* 



CI) Cell-structure and Protoplasm. 



Protoplasm.t— In a report of very elaborate researches on the nature of 

 protoplasm. Dr. G. Berthold maintains the old view that it is to be re- 

 garded as a highly complex emulsion, differing in consistence in the 

 different cases ; and that the forces upon which the changes of form, 

 internal movements, and so forth, depend, are the same as those which 

 determine whether a fluid shall assume the form of a drop, or di'ops, or 

 spread out and wet another body, and so on — in fact, the forces concerned 

 in surface-tensions. 



To take an example of a typical cell : — a spore of Equisetum may be 

 regarded as a system of concentric layers. First there is a central nucleus ; 

 then various layers of protoplasm, of which the innermost is colourless 

 and contains certain minute granules, the second is thicker and carries the 

 chlorophyll-corpuscles, the third is hyaline, and contains lenticular refrac- 

 tive bodies of peculiar nature ; then follows the cell-wall, if nothing further. 

 The cell-wall is usually composed of three or more layers. If we consider 

 the cells of a tissue, Berthold points out that a given partition membrane 

 must be regarded as dividing and belonging to two symmetrical plasmatic 

 systems, and as being their middle and innermost layer. 



But all cells are not systems of concentric layers. Not only are 



* Tills subdivision contains (1) Cell-structure ami Protoplasm; (2) Other Cell- 

 contents; (3) Secretions; (4) structure of Tissues ; and (3) Structure of Organs. 



t Berthold, Ci., ' Studicn ii her Protoplasinamcchauik,' Leipzig, 1880. See Prof. II. 

 Marshall Ward in Nature, xxxv. (Ib87) p. 300. 



