Mat 13, 1910] 



SCIENCE 



747 



steps to secure such action as would prevent their 

 further introduction and spread. Dr. H. Metcalf, 

 Dr. H. T. Gtissow, Professor H. L. Bolley, Pro- 

 fessor A. D. Selby and Mr. W. A. Orton were 

 appointed. 



A joint session with Section G of the American 

 Association for the Advancement of Science for 

 the reading of papers was held Thursday after- 

 noon, December 30, and two separate sessions 

 were held Friday, December 31. Abstracts of the 

 papers read follow: 



Morphology and Life History of Puccinia mat- 

 vacearum Mont.: Mr. J. J. Tatjbenhaus, Dela- 

 ware Agricultural Experiment Station. 

 Morphology. — The mycelium of this fungus is 

 septate, branched and intercellular. It is very 

 rich in oil globules and protoplasm which gives 

 it a red orange color. Haustoria are rarely 

 found. A characteristic mycelial cushion is 

 formed under the epidermis of the host. This 

 cushion is made up of large mycelial threads 

 irregularly interwoven and at the tips of which 

 knobs are formed. Each knob bears from two to 

 five teleutospores, each teleutospore starting as a 

 little bud. The teleutospores are found to greatly 

 vary, in both form and. shape. One-celled and 

 three-celled are fairly common, while four-celled 

 teleutospores are found more rarely. The sporidia 

 are formed in two ways: First, the promycelium 

 divides into four pear-shaped bodies which bear 

 the sporidia. Second, the promycelium breaks up 

 into four cells which separate and each cell forms 

 and bears a sporidium. 



Life History. — The fungus is carried over win- 

 ter as developing mycelium, as hibernating 

 teleutospores and with the seeds. Late in the 

 fall young sprouts are formed at the base of the 

 hollyhock. These soon become infected. The 

 plants are covered up with a mulch to protect 

 them from the cold. The young sprouts grow 

 considerably under the mulch. During late fall 

 the leaves do not show evidence of infection. 

 This becomes evident during the winter when the 

 young sori appear as white dots which become 

 more yellow and finally bear mature teleutospores 

 early in the spring. Infected hollyhock leaves were 

 gathered, part of which were kept out of doors 

 and part in the culture room. Grcrmination tests 

 were made every month from that material. The 

 teleutospores germinated and produced an abun- 

 dance of sporidia in the middle of the winter as 

 well as early in the spring, proving that the 

 fungus may be carried over as hibernating teleuto- 

 spores. 



In the fall of 1908 badly diseased seeds of 

 Malva rotundifolia were collected and kept over 

 winter in the laboratory. Early in the spring 

 these seeds were planted in flats in the green- 

 house, where no outside infection could take place. 

 Ten days after germination half of the seedlings 

 showed well-developed sori on the cotyledons or 

 on the hypocotyl. By artificial inoculation Puc- 

 cinia malavacearum on the hollyhock is readily 

 communicated to the Malva rotundifolia or vice 

 versa. 



Common Names for Plant Diseases: Dr. F. L. 

 Stevens, North Carolina Agricultural and 

 Mechanical College. 



The methods of common naming of plant dis- 

 eases in America, Germany and France are dis- 

 cussed and the necessity of uniform usage among 

 American plant pathologists is urged, and the 

 appointment of a committee to draft rules for 

 the nomenclature of plant diseases is recom- 

 mended. 



Malnutrition Diseases of Cabbage, Spitiach and 

 other Vegetables: Mr. L. L. Haeter, Bureau of 

 Plant Industry. (Read by Mr. W. A. Orton.) 

 This disease was first observed by Mr. W. A. 

 Orton in several of the trucking sections along 

 the Atlantic coast, where it afi'ects nearly all 

 vegetables where intensive cultivation is prac- 

 tised. Every attempt to isolate an organism that 

 might be responsible for the trouble resulted in 

 failure. 



The disease is characterized as follows: The 

 plants grow poorly, have small, stubby roots with 

 few or no laterals. The chlorophyll disappears 

 from between the veins and around the margin of 

 the leaf, while along the midrib and veins the 

 color remains normal. The leaves are very much 

 thickened and brittle. By quantitative analysis, 

 diseased material was found to contain 77 per 

 cent, more starch than the normal, which can be 

 accounted for by the fact that the translocation 

 diastase has probably been so weakened as to be 

 unable to act upon starch. 



The disease occurs only in soils containing a 

 large amount of acids, which doubtless interfere 

 with the normal activities of the plants and the 

 growth of microorganisms. 



The application of calcium carbonate in the soil 

 results in the development of normal plants. 

 Contributions to the Life History and Structure 

 of certain Smuts: Dr. B. F. Lutman, Univer- 

 sity of Vermont. 



This work was suggested by the recent discov- 

 eries in the sexuality of the rusts and is an 



