334 BOTAXICAL GAZETTE [april 



agent than do the checks. He interprets the first change as due to greater 

 permeability of plasmolytic agents, and the second change as due to loss of 

 solutes during the period of higher permeability. Sztics 28 finds that aluminum 

 salts render cells more difficult to plasmolyze because they harden the proto- 

 plasm, although they really decrease its permeability. One must look out 

 for a similar condition with electrical stimuli. The experiments are qualitative 

 but suggest the need of very careful quantitative studies. — Wm. Crocker. 



Texas root rot fungus. — Duggar 29 has investigated the causal organism of 

 one of the most destructive of the cotton diseases, an organism which seems to 

 be confined largely to Texas, where the average losses have been variously 

 estimated to be $2,000,000 to $3,000,000. In addition to the attacks on cotton, 

 the fungus damages such crops as alfalfa, beans, sweet potatoes, and certain 

 orchard fruits. As illustrating the omnivorous habit of the fungus, Duggar 

 enumerates a list of nearly 30 host plants (trees, shrubs, and herbs) already 

 noted as used by the fungus. The chief feature of the disease is the sudden 

 wilting and dying of the affected individuals. The fungus was described by 

 Shear as Ozonium omnivorum, but Duggar concludes that it should be trans- 

 ferred to Phymatotrichum. In the revised description of the species the 

 habitat is stated as follows: "Hyphae on living roots of many plants and in the 

 soil; conidial stage on soil in the vicinity of diseased plants." — J. M. C. 



1 



Embryo and seedling of Dioscorea. — Miss Smith 30 has investigated the 

 embryo and seedling of Dioscorea villosa, a genus long known through the* 

 work of Solms-Laubach as furnishing evidence of a "second cotyledon," or 

 at least a seedling structure quite different from what had come to be regarded 

 as the monocotyl type. Miss Smith traced the development of the embryo 

 to the spherical 4-celled proembryo, and then followed the appearance of the 

 organs. She observed no cotyledonary ring, and claims that the single coty- 

 ledon originates as a terminal structure. It may be stated that the course of 

 the vascular strands suggests that the leaf called the "first secondary leaf" 

 occupies the position of a "second cotyledon," which would make the growing 

 point of the stem a terminal structure, and both cotyledons lateral. This, 

 however, is a matter of interpretation in connection with material. — J. M. C. 



Vitality of moss protonema. — Miss Bristol 31 has discovered some remark- 

 able cases of the retention of vitality by the protonema of mosses. In samples 

 of soils obtained from various places for the purpose of ascertaining by means 



28 Rev. in Bot. Gaz. 56:245. 1913. 



2 « Duggar, B. ML, The Texas root rot fungus and its conidial stage. Ann. Mo. 

 Bot. Gard. 3:11-23. Jigs. 6. 1916. 



*° Smith, Pearl ML, The development of the embryo and seedling of Dioscorea 

 villosa. Bull. Torr. Bot. Club 43 : 545-558. pis. 31-34. 1916. 



31 Bristol, B. Muriel, On the remarkable retention of vitality of moss protonema. 

 New Phytol. 15:137-143. Jigs. 3. 19 16. 



