1904 | CURRENT LITERATURE 233 
partly filled with the contents of the vacuoles that assist in the cleavage ; 
(5) formation of walls about the spores and columella, and, in the case of 
Rhizopus, the secretion of an intersporal slime; (6) partial disintegration of 
the nuclei in the columella.—J. M. C 
WHAT SEEMS a careful study of the effect of certain external conditions 
upon the evolution of oxygen by some green water plants has been made by 
Pantanelli.% He finds that the curve of oxygen production with varying light 
intensity shows a distinct optimum (at about one-fourth the intensity of direct 
sunlight), beyond which it falls as light increases, unless the supply of CO, 
is varied at the same time, in which case the optimum would be displaced in 
the direction of weaker light with less CO., and toward the stronger light 
with more CO,. The regulation of the activity of the chloroplasts is not 
instantaneous, five to ten minutes passing before a change in their activity 
can be ascertained. Ultra- “optimal light — dpe Oca alt rire and, 
if excessive, prod tion and d fO,. Further- 
more, and independently of these changes, it produces in the chloroplasts 
phenomena of fatigue like those of an isolated muscle, which pass away 
gradually after the return of normal conditions, the slower the more complete 
the fatigue, By light intense enough to diminish the decomposition of CO, 
the chlorophyll pigment is attacked. After such injury it is never reformed. 
e€ evolution of OO, increases with the increased content of CO, in the water 
to an optimum, and then decreases, unless the light varies correspondingly. 
The bubbles of gas given off, however, continue to increase beyond the CO,- 
optimum, but contain more and more CQ,, which merely diffuses through the 
plant unchanged. 
'  Pantanelli also finds that various solutes exercise a marked influence upon 
photosynthesis, for which details the original must be consulted. He holds 
the chief result of his work to be the demonstration that the plasmatic portion 
of the chloroplasts works, tires, and recuperates, the chlorophyll remaining 
primarily wholly indifferent; but if the plasmatic stroma becomes injured, the 
chlorophyll immediately suffers photochemical oxidation. Normally, how- 
ever, its lability does not appear, because it is constantly protected by the 
piasma. Nothing, he thinks, indicates that in strong light chlorophyll is con- 
tinually decomposed and regenerated—an assumption of those who look 
upon chlorophyll as a sensitizer.— C. R. B 
ITEMS OF TAXONOMIC INTEREST are as follows: G. F. ATKINSON (Ann. 
Mycol. 1: 479-502. pl. 10. 1903) has discussed the genus Harpochytrium in 
the United States.— F. v. HOHNEL (idem 522-534) has described the follow- 
ing new genera of fungi: Bresadolella (Nectriaceae), Myxolibertella (Melan- 
Conieae), Sporodiniopsis (Hyphomycete), Cirrhomyces (Dematieae), Aegeri- 
fopsis (Tubercularieae), —R. PrLGerR (Engler’s Pflanzenreich IV. 5. p. 117. 
** PANTANELLI, Enrico, Abhangigheit der ee belichteter 
Pflanzen von dusseren Bedingungen. Jahrb. Wiss. Bot. 39: 167-228. 19 
