620 



SCIENCE 



[N. S. Vol. XLVII. No. 1225 



The perfecting principle: L. H. Bailey, LL.D., 

 late professor of horticulture, Cornell University. 



Medicinal plants — present and future supplies: 

 Henky Kraemer, Ph.D., head of department of 

 pharmacology. University of Michigan. 



Parasitism among the red algw: William A. 

 Setchell, Ph.D., professor of botany in the Uni- 

 versity of California. Parasites among the mem- 

 bers of the BhodophyceEe, or Eed Algte, are be- 

 coming more and more known. The author has 

 been paying special attention to these parasites 

 for some years. Of some 51 species, old or new, 

 known to be wholly or partially parasitic, 39 are 

 on plants of the same family of Red Algae, 8 

 others are on Red Algte not of the same family but 

 with some on hosts fairly nearly related ; while only 

 4 are parasitic on hosts belonging to other groups 

 (brown or green algse). These facts seem signifi- 

 cant as to the origin of these parasites. The epi- 

 phytic red algEe often penetrate the host plant 

 which is commonly also one of the Red Algas, but 

 also may be either brown or green. Some light 

 may be thrown on the origin of red parasites, par- 

 ticularly of those parasitic on close relatives by 

 the behavior of the tetrasporangia of Agardhiella 

 tenera. As described by Osterhout in 1896 the 

 zonate tetrasporangia germinate as a whole even 

 after division into tetraspores, and produce dwarf 

 unbranehed plantlets which penetrate the tissues 

 of the parent plant by basally produced rhizoids. 

 The plantlets produced are largely antheridial, but 

 some are cystooarpio and some even tetrasporic. 

 Such mutations as these plantlets of Agardhiella 

 seem to represent, accompanied by a greater or less 

 degree of chlorosis, go far toward indicating a 

 possible origin of these parasites on closely related 

 hosts. 



Friday Afternoon, April 19; Albert A. Michelson, 

 Ph.D., ScD., LL.D., F.E.S., Vice-president, 



in the Chair 

 The genus Galera in North America, with pre- 

 liminary notes of some new species of Agarics: 

 George F. Atkinson, Ph.D., professor of botany, 

 Cornell University. Galerula is a genus or yellow- 

 spored Agaricacess including small plants or those 

 of medium size, but slender in form, and fragile. 

 The species have no claim to rank or economic im- 

 portance, whOe their ecological r8le as saprophytes 

 is not large owing to the comparatively small num- 

 ber of individuals. Many species are usually asso- 

 ciated with mosses on logs or ground in the woods 

 or swamps. A number of species occur on dung 



heaps or in recently manured grass lands. The 

 larger number of species are some shade of yellow, 

 or tawny, or ochraceous. In taxonomic works the 

 genus is usually divided into sections according to 

 external characters and ecological relations. By 

 this method the species are not grouped according 

 to their real aflSjiities, and in a few cases forms 

 not closely related are assembled under a single 

 specific name. A high degree of internal struc- 

 tural differentiation has taken place in the evolu- 

 tion of the species. In the present study this van- 

 tage point has been employed to group the species 

 into sections more nearly in accord with their true 

 relationships. Between 50 and 60 species are rec- 

 ognized in North America. 



Temperature, imbihition and growth: D. T. Mac- 

 Dougal, Ph.D., LL.D., director of the department 

 of botanical research, Carnegie Institution of. 

 Washington. The effects of temperature upon 

 swelling of biocoUoids consisting of agar, and pro- 

 teins have been previously described. With these 

 results were given measurements of the swelling of 

 sections of Opuntia already in a turgid condition 

 with their imbibition capacity nearly satisfied, and 

 not in a growing condition. Special tests were ar- 

 ranged by which the effect of changes in tempera- 

 ture upon the swelling of sections of growing cell- 

 masses and upon the growth of similar masses 

 should be determined. Elongation by growth of 

 the stems in question was at the rate of 5.2 mm. 

 daily at 16°-18° C. and 11-17 mm. daily at 30°- 

 32° C. The increase amounted to a doubling, more 

 or less, for a rise of 10° C. The swelling in trans- 

 verse sections of similar material was 4.9 per cent, 

 at 17°-19° C. and 7.5 per cent, at 30°-31° C. in 

 distilled water: and 4.9 per cent, at the lower tem- 

 perature in acidified potassium nitrate and 9.5 per 

 cent, at the higher temperature. The increase by 

 swelling transversely was therefore slightly less 

 than double with a fair inference that it would 

 have been greater in the axis of elongation or 

 growth. It is to be seen therefore that in the 

 elongation of the vegetative axes of plants, the 

 temperature effect is a very complex one, and that 

 the accelerating effect of rising temperature may 

 be primarily an increase in absorption capacity by 

 altered metabolism including lessened accumula- 

 tions of acids. 



Variation in ilueberry hybrids: Frederick V. 

 Coville, curator of the U. S. National Herbarium, 

 Department of Agriculture, Washington, D. C. 



Organization, reproduction and heredity in 

 Pedia-strum: Robert A. Hakper, Ph.D., professor 

 of botany, Columbia University. 



