Simplest Forms of Life. 305 



When the spleen is removed an abnormal condition is induced 

 and it would be difficult to assert where the red corpuscle meets its 

 death. 



Therefore, the origin of the very first red corpuscles is from 

 nucleated cells in the vascular area ; a little later in embryonic 

 life, from cell division. Their origin in the adult is from the 

 leucocytes ; the latter, becoming impregnated with haemoglobin, 

 owing to the action of oxygen, change to biconcave discs ; the 

 nucleus of the white cells becoming gradually changed into the 

 formed material of the red. Their death is owing to a mechanical 

 cause in the spleen, and probably occurs, to some extent, in the 

 liver also. This paper embodies the views of the writer, founded 

 upon the opinions of various authors as well as original investi- 

 gations made at this laboratory. 



Physiological Laboratory, 



University of Michigan. 



THE SIMPLEST FORMS OF LIFE. 



BY B. EVFF.RTH. 



{^Translated from the German for this Journal, with additions.) 

 {Continued.) 

 II. FAMILY. DESMIDIACE.F:. 

 Cells single, or (seldom) united in series, of various, often ornamental, 

 shapes, generally divided into symmetrical halves by a constriction. Di- 

 vision by separation of the two parts, and growth of the connecting piece 

 between them into two new halves. Spores formed by copulation without 

 the mother cells, from both of which the entire plasma escapes to form a 

 single spherical zygospore, which becomes surrounded by a thick, often 

 verrucose or spinous, membrane. Manv species of elongated form possess 

 round vacuoles at each end, with small, stronglv refracting, particles in 

 constant molecular motion. 



The numerous forms live generally singly in ponds and ditches. 

 Cells not in two symmetrical halves, long, cvlindrical. 



Chlorophyll in the axis of the cell, Gonatozygon, d. B. 



Chlorophyll on the cell walls, Gcnicularia, d. B. 



Cells divided, without or within, into symmetrical 

 halves, 

 in chain or ribbon-like families, 



generally with gelatinous coating, compressed, 



flat, Spharozosma, Corda. 



