a a a a 
RT IRAE, I PRS ee ee a ae ee ee eT Re MPS Mee Fe ew eR ee 
1899] CURRENT LITERATURE 75 
wood apparently sound. In both, also, a fungus mycelium was found, which 
flourishes within the diseased centers, but no characters appeared by which 
it could be determined. It is interesting to note the fact that these two treés, 
similarly affected, are the representatives of a race largely extinct, and grow 
in different parts of the country. 
The same author (of. czt. 6-70) has also discovered a peculiar sclerotioid 
disease of beech roots. Small tubercles were found attached to the fibrous 
roots, and upon examination these were found to be a twisted and contorted 
mass of rootlets invested by a sheath. It was impossible to determine the 
fungus, but it seemed probable to the author that it is distinct from those 
forming the mycorhiza.— J. M. C 
MEssrs. FARMER and WILLIAMS have continued their contributions to 
the life-history and cytology of the Fucacez by publishing a second paper” 
which deals with the development of the oogonia and oospheres, the phenom- 
ena of fertilization, and the early segmentation stages of the oospore, espe- 
cially in the genera Fucus, Ascophyllum, and Pelvetia. The more interesting 
subjects discussed are the reduction in the number of chromosomes, the 
appearance and behavior of centrospheres and centrosomes, the formation of 
the walls of the oogonia, oospheres, and germinating oospore, and the part 
played by mucilage in bringing about the extrusion of the oospheres. 
The reduction of chromosomes occurs in the papilla which is cut off to 
form the rudiment of an oogonium. This was also shown by Strasburger to be 
the case in Fucus. In the three successive mitoses by which the eight 
magnon nuclei are formed, the reduced number of chromosomes is retained. 
Prominent centrospheres in the form of converging cytoplasmic radiations 
“re present in every mitosis, whether of the oogonium or segmenting oospore. 
ee Could not be traced back to preexisting centrospheres, but appeared to 
‘rise independently by the activity of the protoplasm, and to disappear again 
nhl Though the centrospheres are cytoplasmic, the spindle 
between them is intranuclear in origin. Centrosome-like structures were 
— seen within the centrospheres, but their number was not constant. 
aps was no indication that the centrospheres of the first oosporic division 
erived from the spermatozoid. 
Se Peas polyspermy were observed that it is certain but one a 
newly ones eee on oosphere. The existence of a wall aroun : ¢ 
ttaheServest C €8§s was conclusively demonstrated ; such eggs burst : - 
treated merely a. water to fresh, whereas unfertilized eggs similarly 
anes nterestin ? sen os ee ilizati observed in 
Halidrys, Ges & aterce with regard to fertilization were : 
PS of gyrating spermatozoids were seen distributed over the 
10 Phj 
hil. Trans. Roy. Soc., London, B. 190 : 623-645. 1898. 
