312 Journal of Applied Microscopy. 



classify fossil woods on minute anatomical characters were largely set aside when 

 it was discovered that several genera could be found growing on a single tree. 

 Some of the artemisias are separated by pubescence characters, and it is not 

 rare to find a single individual smooth in summer and pubescent in winter ; all 

 gradations can also be found as the habitat varies. A more careful study will 

 surely result in our finding that many of the species of our manuals are but 

 habitat variations. In the light of what we now know about the plasticity of 

 plant structures, it would seem wiser to direct anatomical studies along lines 

 that are more likely to yield profitable results. 



Henry C. Cowles, Chicago. 



.„ . r. r, .. ,x T^. ^ ,T Directions are given for collecting and 



Wood, D. B., M. D. Diatoms. Trans. Vasser ^ '^ 



Bros. Inst, and its Sc. Sect. 7: 66-86, mounting diatoms. They grow in 

 1894-1896. either stagnant or fresh water, at any 



temperature, from that of polar seas to hot springs. They may be obtained by 

 skimming off the brownish scum found on ponds, by squeezing out water weeds, 

 by scraping sticks and stones which are covered at high water, or from the mud 

 of the filter beds at pumping works, or in other places. The material is put in 

 a dish of water and after it has settled the water is decanted. This is repeated 

 until the water will clear in about one-half hour. The sediment is then treated 

 with an equal bulk of sulphuric acid, after which bichromate of potash is added 

 until all action ceases. After a couple of hours the acid is washed out. To 

 separate the diatoms, place the cleaned sediment in a glass dish with water and 

 when the water becomes clear give the dish a slight rotary motion. This will 

 bring the diatoms to the top, when they may be removed with a pipette and 

 placed in alcohol. To mount, place a number in distilled water, evaporate a 

 few drops of the mixture on a cover-glass, which is then mounted on a slide in 

 Canada balsam. e. m. b. 



• 



_ . . „ -^ , . , .^ This paper consists principally of a 



^acnarias, b. Ergebmsse der neueren Unter- ^ ' 1 1 y 



suchungen liber die Spermatozoiden. Bot. brief review of recent literature on the 

 Zeit. 57: 1-6, 1899. development of spermatozoids with 



special reference to centrosomes and blepharoplasts. In closing, he refers to 

 the fact that recent investigators of fertilization in Angiosperms have not been 

 able to find centrosomes, and he adds the suggestion that it is not impossible 

 that reinvestigation may reveal the centrosomes again where they, have been 

 missed temporarily. c. j. c. 



RECENT LITERATURE. 



Belajeff, Wl. Uelier die mannlichLMi I'rothal- Nelson, E. M. On the Evolution of the Micro- 

 lien der Wasserfarne. (Hydropterides). Kot. scope. Jour. Queckett Mic. Club. 7: 98-117. 

 Zeit. 56: 141194. pi. 8-9, 1898. figs. 10-23, 1898. 



Dittrich, 0. Zur luitwickelungsgeschichte der Reed, J. W. The Aecidium stage of Uromyces 

 Helvellineen. Beitriige zur Biol. d. I'flanzen. pisi. Jour. Queckett Mic. Club. 7: 65-74, 1898. 



/ J ■ 1 • 4 5' ^ 9 • Saunders, De A. Phycological Memoirs. Proc. 



Eriksson, Jakob. Studien liber den Ilexen- Calif. Acad. Sci. [Contributions to Biology 



besenrost der Berberitze. (Puccinia Arrhena- from the Hopkins Seaside Laboratory of 



theri. Kleb.) Beitrage zur Biol d. Pflanzen. Leland Stanford, Jr., University XVI.] Proc. 



8: i-i6.pl. 1-3, 1898. 3rd. Ser. Botany I: pp. 147-168. pi. 12-30, 



1898. 



