and Laboratory Methods. 2-175 



CURRENT BOTANICAL LITERATURE. 



CHARLES J. CHAMBERLAIN, University of Chicago. 



Books for Review and Separates of Papers on Botanical Subjects should be Sent to Charles J. 

 Chamberlain, University of Chicago, Chicago, ill. 



Davis, Bradley Moore. Oogenesis in Sapro- The original collection bore oogonia 



legnia. Bot. Gazette, 35: 2^^-240, 'J20-'?4Q, ., . ^, .,. , , . . 



pis. q-io, 1903. Published also in Decenni- ^ith few antheridia, but by cultivating 

 nal Publications, The University of Chicago, on a rich substratum — raw beef or 

 -5 -57. 9 J fresh insects -the antheridial filaments 



become more numerous. On boiled eggs and dried beef oogonia are formed in 

 great numbers, but there are no antheridia. After a time all cultures cease to 

 bear oogonia and antheridia and produce only zoosporangia. Oogonia can 

 always be produced by placing cultures with zoosporangia in such conditions 

 that the hyphae are not submerged. This can be done by placing material on 

 cold agar-agar, where the filaments out of water soon develop oogonia. 



In fixing, 1 per cent, chromo-acetic acid caused immediate contraction of the 

 protoplasm. A solution of }{ per cent, chromic acid and y\j per cent, acetic 

 gave the best results, having advantages over Flemming's, Merkel's, corrosive 

 sublimate, sublimate acetic, iridium chlorid or picric acid. Safranin and gen- 

 tian violet were used for staining. 



The study of oogenesis was made upon apogamous material of Saproleguia 

 mixta. The resting nucleus has essentially the same structure as in the higher 

 plants. In the coenocytic oogonium there is one simultaneous mitosis, the spin- 

 dles being intranuclear. There are four chromosomes and no centrosomes. 

 The differentiation of the egg origins {Anlage) takes place around coenocentra 

 which exert a chemotactic influence upon the nuclei in their vicinity. Gener- 

 ally, one nucleus lies close to the ccenocentrum and increases in size while all 

 other nuclei in the ^^^^ origin degenerate, so that eggs are usually uninuclear. 

 Trinucleate eggs are sometimes found and binucleate eggs are not uncommon, 

 but the binucleate condition need have no relation to sexuality. In the forma- 

 tion of eggs, the protoplasm collects in denser masses about the coenocentra with 

 their accompanying nuclei. The protoplasm between the egg origins becomes 

 less dense and a series of vacuoles appears which separate the origins from each 

 other and allow them to round off as independent eggs. 



The investigations upon sporogenesis resulted in a general confirmation of 

 the accounts of Rothert, Hartog and Humphrey. 



More then half of the paper is devoted to a theoretical discussion of homo- 

 logies and relationships among the Phycomycetes and Ascomycetes. The oogo- 

 nia and antheridia of Peronosporales, Saprolegniales and Pyronema are the 

 homologues of gametangia and of the ccenogametes of Mucorales. In the evolu- 

 tion of the coenogamete, eggs with a larger number of nuclei are regarded as 

 more primitive, there being a tendency to reduce the number of nuclei, rather 

 than the reverse. The Mucorales, Peronosporales and Saprolegniales can be 



