igig! CURRENT LITERATURE 279 



the protonema can live for 7 months without producing a leafy shoot. He 

 observed also the movement of "chomatophores," which became scattered in a 

 day w-hen the protonema is placed in light, and when the direction of light is 

 changed they all turn toward it in 7-10 days. Blue and violet light proved to 

 be more favorable than any other of the visible rays, excepting of course white 

 light. The optimum temperature for the development of the leafy shoot is 

 16-25° C.; the protonema does not die so long as the temperature is above 

 — 20 . 5° C, but the leafy shoot dies at — 18° C. The spore at a temperature of 

 16-25° C. germinates in one month. — J. M. C. 



Angiosperm wood lacking vessels. — Bailey and Thompson,** in continuing 

 their work on certain genera of angiosperms in which true vessels are absent 

 from the normal wood of the stem, have obtained additional evidence. Their 

 attention had been called to the occurrence of vessel-like structures in injured 

 roots of a species of Dritnys, which might indicate that the ancestors of the 

 3 genera investigated possessed true vessels. An examination of these struc- 

 tures has led to the conclusion that they are not vessel-Uke in structure, but are 

 typical tracheids, which occur as well in uninjured stems of the 3 genera. They 

 maintain, therefore, that true vessels do not occur in the xylem of these genera, 

 and that there is no evidence that their ancestors possessed true vessels. — 

 J. M. C. 



Permeability. — Paine and Saunders*^ find, that the testa of the pea is 

 impervious to various reagents dissolved in water (copper ferrocyanid, sodium 

 chloride, safranin) due to a waxy bloom deposited on the outer surface. This 

 bloom is easily rubbed off so that the testa becomes pervious. In the wrinkled 

 peas the bloom rubs off on the w-rinkles, leaving the depressions still impervious, 

 while in the smooth pea the bloom rubs off uniformly on the whole surface. It 

 is interesting to find such a superficial layer responsible for the peculiar per- 

 meability characters of seed coats, for these characters are generally deter- 

 mined by deeper layers. — ^Wm. Crocker. 



Agaricaceae of Michigan. — Kauefman,*^ in connection with his very full 

 presentation of the Agaricaceae of Michigan, has monographed Russida (pp. 

 118-167), Pholiota (pp. 289-314), and Cortinarius (pp. 314-442), as represented 

 in the state. In Russula he recognizes 53 species, 3 being new and 27 edible; 

 in Pholiota 26 species, 4 of which are edible; in Cortinarius 154 species, 13 of 

 which are new and 10 edible. As an illustration of the activity of Charles 



" Bailey, I. W., and Thompson, W. P., Additional notes upon the angiosperms 

 Tetracentron, Trochodendron, and Drimys, in which vessels are absent from the wood. 

 Ann. Botany 32:503-512. pi. 16. figs. p. 1918. 



'i Paine, S. G., and Saunders, L. M., On a peculiarity exhibited by the testa of 

 wrinkled peas. Ann. Botany 32:175. 1918. 



^■'KAurFMAN, C. H., The Agaricaceae of Michigan. Mich. Geol. and Biol. 

 Survey, Publ. 26. Biol. Series 5. December 1918. 



