1902] CURRENT LITERATURE 461 



table of contents, and its value is therefore much impaired. Following a 

 rambling introduction, partly historical and partly descriptive of structure 

 and methods, is a description of the genera and species. This account is 

 lengthy and so deficient in keys and synopses as to be of little value to the 

 general student. The second part of the paper contains five chapters devoted 

 to structural details, movements, nutrition, and methods of reproduction. As 

 is well known, the Euglenineae present a wide range of variation in their 

 feeding habits. Only one of three families, the Euglenaceae, have a halo- 

 phytic nutrition, the other groups entirely lacking chlorophyll. One family, 

 the Peranemaceae, engulfs its food as solid material in an animal-like fashion. 

 Other forms, the Astasiaceae, are saprophytic, preferring water foul with 

 organic matter. The Euglenaceae are especially interesting. Although 

 generally containing chloroplasts, they may under certain conditions adopt 

 saprophytic habits, when the chlorophyll disappears and the cell is quite 

 devoid of pigment. The plastids in such cells are believed to remain as 

 leucoplasts, which regain their green color under proper environment. Sorhe 

 of the species are normally without color. 



Eitglena gracilis is remarkable for its powei of adaptation to food rela- 

 tions. It becomes colorless under saprophytic conditions, as when cultivated 



* 



m sugar solutions away from light, but it regains its green color very readily 

 if brought back to a more normal environment. There are differences of 

 opmion as to the behavior of the plastids. Former writers have held that the 

 chloroplasts simply lose their color, becoming leucoplasts, which remaining 

 m the cell as organized bodies, assume again the chlorophyll when such was 

 reformed in the organism, Dangeard believes that the chloroplasts may dis- 

 appear entirely and be formed again de novo. 



The chief events of nuclear division are as follows: The resting nucleus 

 consists of a nucleolus surrounded by a chromatic spirem which is not 

 clearly divided into segments. At division the nucleus elongates, and 

 the nucleolus stretches into a rod which appears like an axis in the 

 nucleus, the chromosomes arranging themselves parallel to this axis. The 

 substance of the nucleolar axis then gradually draws apart in the center and 

 accumulates at the poles. The chromosomes distribute themselves in xv,^o 

 groups, which gradually separate and gather around the two daughter 



r 



nucleoli and the nucleus thus divides directly. In most cases there is no 

 trace of a nuclear membrane around the nucleus at any period of its trans- 

 formations. — B. M. Davis. 



Farmer and Hill^' have described the anatomy and development of 

 Angiopteris, Marattia, and Kaulfussia. They find that the central cylinder 

 of the stem in the first two genera originates as a solid tracheary rod sur- 



*3 Farmer, J. Bretland and Hill, T. G., On the arrangement and structure of 

 the vascular strands in Angiopteris evecta and some other Marattiaceae. Ann. Botany 

 16: 371-402. pis, 16-18. 1902. 



