472 



SCIENCE. 



[N. S. Vol. XX. No. 510. 



cetella, Cycloporus, Globlfomes, Nigrofomes 

 and Poronidulus. 



' until he has accumulated a greater body of 

 facts on the subject.' 



STUDIES OP SEXUALITY IN BLACK MOLDS. 



Every student of botany in. the last quarter 

 of a century has given some attention to the 

 black molds {Mucoraceae) , some speciesi of 

 which are so common as to be obtainable for 

 laboratory use at any season of the year. Yet 

 while every one has been able to study the 

 gross anatomy of black molds, and the forma- 

 tion of their interesting conidia, their zygo- 

 spores, which are still more interesting, are so 

 diificult to obtain they have rarely been 

 available for study. Whether we regard the 

 sexual organs of black molds as primitively 

 isogamic, or as essentially heterogamic with 

 a degradational approach to isogamy, they are 

 interesting objects of study in the laboratory. 

 Anything which will make it easier to secure 

 these structures is to be regarded as of much 

 importance scientifically and practically. This 

 service has been rendered by Mr. Albert F. 

 Blakeslee in a recent paper published by him 

 in the Proceedings of the American Academy 

 of Arts and Sciences (Vol. XL., No. 4, August, 

 1904), under the title of ' Sexual Reproduc- 

 tion in the Mucorineae.' A preliminary siim- 

 mary of the results of this paper was pub- 

 lished in Science, June 3, 1904, and we now 

 have the full account. The present paper con- 

 tains about 120 pages of text, and is accom- 

 panied by four plates aggregating fifty-eight 

 figures. Here are given the details of many 

 experiments undertaken by the author in order 

 to determine the cause or causes of zygospore 

 formation. The ingenuity of some of these 

 experiments must command the admiration of 

 every one who reads the paper. It will be 

 remembered that the most striking result of 

 Mr. Blakeslee's experiments has been the dis- 

 covery that zygospores of the black molds 

 may be obtained by growing different strains 

 side by side, the zygospores appearing where 

 the hyphae of the two strains intermingle. The 

 practical importance of this discovery will be 

 appreciated by all who have laboratories in 

 which stTidents are at work. The author 

 promises to continue his studies, and reserves 

 an extended discussion of certain problems 



egg formation in green felt (vaucheria). 

 Dr. Bradley M. Davis has made a careful 

 study of egg-formation (oogenesis) in a 

 species of green felt (Vaucheria), one of the 

 common fresh-water algae, and published his 

 results in the August number of the Botanical 

 Gazette. These plants have great numbers 

 of minute nuclei which are not separated by 

 walls, and when the lateral protrusion forms 

 in which an egg is finally to develop, it also 

 contains a large number of nuclei. This pro- 

 trusion (oogone) is soon separated from the 

 rest of the filament by a cross-wall which 

 forms when it is about two thirds its full size. 

 About this time there sets in a degeneration 

 of nuclei resulting in the disappearance of 

 all but one, so that the oogone is eventually 

 uninucleate. The single nucleus increases 

 rapidly in size until ' in the mature egg it is 

 three or four times as large as the original 

 nuclei in young oogonia.' 



The author calls attention to the essential 

 agreement of the process of egg formation in 

 Vaucheria with those of certain phycomyce- 

 tetous fungi {Saprolegnia, Phythium, Perono- 

 spora, Plasmopara, Sclerospora, Albugo and 

 Araiospora). He discusses' the relationship 

 of Vaucheria to other green algae, suggesting 

 its derivation from ancestors whose oogonia 

 were multinucleate. The relationship of the 

 water molds (Saprolegniales) and downy 

 mildews (Peronosporales) presents some diffi- 

 culties, bitt the author calls attention to the 

 fact that they possess many points of similarity 

 to Vaucheria. Their relationship to the 

 molds (Mucorales) is more obscure, but here 

 again similarities are not wanting. The 

 paper is very suggestive, and will repay care- 

 ful perusal. 



RECENT FORESTRY BULLETINS. 



Three bulletins (numbers 47, 48, 49) of 

 much more than ordinary interest have been 

 issued recently by the United States Bureau 

 of Forestry. In the first Professor Bray, of 

 the University of Texas, discusses the ' Forest 

 Resources of Texas.' He calls attention to 



