1902] CURRENT LITERATURE 315 
__ Friedel,” who claimed that he had observed, apart from the living plant, the 
gas exchanges which are associated with photosynthesis. Macchiati® has 
__ liscussed the significance of Friedel’s results without adding many new facts 
_ ofhisown. Friedel"? and Harroy~ have repeated the earlier experiments of 
: the former and obtained negative results. Friedel attributes this to the general 
_ Weakening of synthetic processes in autumn, and promises to experiment on 
a large scale in the coming spring. He observed that young Pelargonium 
leaves show an activity in early summer that is twenty times that of similar 
young leaves in autumn, and that one scarcely ought to expect dead leaf 
material to exhibit gas exchanges at such an unfavorable period. Harroy, 
who repeated Friedel’s experiments exactly and then improved upon the 
oS latter's experimental methods, concludes that Friedel’s claim is premature, to 
‘Sy the least, though he admits its plausibility. H. C. CowLEs. 
ue Mitosis in the cells of Spirogyra presents difficulties that have led toa 
Rumber of investigations with widely different results and much confusion. - 
‘The last extensive paper on the subject is by Wisselingh.* The chief diffi- 
stag the past have been the interpretation of nucleolus-like structures. 
“isselingh finds generally one nucleolus for each nucleus, but sometimes 
(‘0 or more of varying sizes. Each has a membrane and contains a closely 
‘network, shown in certain stages of development to be made up of two 
8 threads. The nucleolus of Spirogyra therefore shows many resem- 
‘i structure to a nucleus. Outside of the nucleolus is a network fill- 
eaudegene 
ing Temainder of the nucleus. eee 
There are two forms of mitosis, one with the formation of segments and 
emteg The segments are generally twelve in number, two coming 
the nucleolus or two nucleoli, and the remainder from the nuclear n 
‘*hese gather to form a nuclear plate at the metaphase of ‘mm 
that these segments are chromosomes, we then have in Spi 
hose nucleoli are chromatic in character. However, the ch 
“xplained,— B, M. Davis. — 
~” OF TAXONOMIC INTEREST are as follows: R. CuopaT and 
ie Herb. Boissier II. 2 : 281-296. 1902) have begun @ cr 
. 
of these bodies is not established, nor are all the stages of mitosis — 
oe the plants of the Argentine Republic collected by 
sof North America —E. L. GREENE (Ottawa vat 
ae. 6 9 Compt. Rend. 133: 
Ot Ital. rg0x : 323-335. = Compt. Rend. 133! 
‘Ueber Kerntheilung bei Spirogyra. II. ‘Flora 87: 
