176 



SCIENCE. 



[Vol. XIII. No. 318 



micro-organisms, and especially the bacillus of tuberculosis. They 

 report that they have found nothing of a harmful character, and 

 have arrived at the conclusion that the danger of spreading infec- 

 tion by means of circulating libraries is very slight. They recom- 

 mend, however, that books should be well dusted before being 

 read, and that the fingers should not be wet in the mouth in order 

 to turn the leaves, ff the experiment is correctly reported, the au- 

 thorities of Dresden are not justified in deducing any such infer- 

 ences. The material which may accumulate in the form of dust 

 on " unused books," and that which may collect on books in in- 

 fected rooms, are of a totally different character. To determine 

 the danger from the use of these latter books, another series of ex- 

 periments must be made, and, in the present state of our knowledge 

 as to the germs of infectious diseases, not much could be expected 

 even from such experiments. The germs of measles, scarlet-fever, 

 and small-pox, which diseases are known to be propagated by 

 articles of wearing-apparel which have been exposed in infected 

 rooms, have never been recognized, and the search for them in the 

 dust which has collected on books would doubtless be as futile as 

 it has been elsewhere ; but there is no a priori reason why such 

 books might not be carriers of contagion equally with clothing and 

 furniture. The advice given to dust books well before reading 

 them, in order to avoid danger, is, if the Dresden authorities are 

 correct in saying that such dust is harmless, entirely unnecessary, 

 while, if the dust should be infected, it would be the best possible 

 way to spread the infection. Books which have been in an infected 

 room, especially if they have been opened, should be destroyed. 

 It is practically impossible to disinfect them. 



The Loco-Weed. — Readers of Science have from time to time 

 written us regarding the " loco-weed " and its poisonous proper- 

 ties, and we have recorded every thing which could be learned 

 about its effects on animals and men. In Vol. IX. p. 32, we referred 

 to a curious affection which exists among horses in north-western 

 Texas, known as "grass-staggers," which is caused by eating the 

 " loco-weed," which gives rise to the saying that the horses are 

 " locoed." The Indians believe that an insect is the cause of the 

 disease, but competent investigators have failed to tind any insect 

 life upon the plant. In Idaho the same disease is found, and is 

 treated by amputation of the tails of the affected animals [Science, 

 ix. p. 306). Francis H. Snow of Lawrence, Kan. {Science, ix. p. 

 92), refers to observations which tend to support the idea that in- 

 sects are connected with the causation of the disease. Professor 

 Sayre of the University of Kansas was said to be making an ex- 

 haustive study of the " loco " problem. Dr. Mary Gage Day of 

 Wichita, Kan., has recently made a number of experiments upon 

 healthy cats to test the toxic qualities of the weed, and has com- 

 municated the results to the New York Medical Jotirnal. The 

 " loco-weed " is a popular name given to Astragalus niollissijmes and 

 Oxytropis Lamberti. In the experiments of Dr. Day, a decoction 

 of the roots, leaves, and stems of plants gathered in September 

 was used. The result of feeding the decoction to a kitten was to 

 produce diarrhoea, vomiting, convulsions, paralysis, and, at the end 

 of twenty days, death. After death, ulcers were found in the 

 stomach and intestine. In another experiment with a more con- 

 centrated decoction, on a full-grown cat, the symptoms were much 

 the same, the cat dying on the thirteenth day. Professor Vaughan 

 of the University of Michigan made experiments on frogs and 

 kittens, injecting the decoction under the skin, producing death. 

 With reference to the character of the plants at different seasons 

 of the year. Dr. Day is convinced, by numerous experiments on 

 material gathered in different months, that the greatest amount of 

 poison is present in the autumn and winter, after the seeds have 

 ripened, and that the explanation of the ranchmen, that the " loco " 

 disease is more prevalent in the autumn and winter because the 

 animals eat more of the weed from the scarcity of other food, is 

 only a partial explanation. The greater toxicity of the plants at 

 that season she believes to be a very important element. From 

 the facts and experiments detailed, the following conclusions are 

 drawn: l. There is some poison in "loco-weed" which may 

 cause the illness, and, if sufficient quantity is taken, the death, of an 

 animal. 2. This poison is contained in the decoction obtained 

 from the plants, and, by systematically feeding it to healthy cats, 



cases of " loco " disease may be produced. 3. From the large 

 quantity of the plant or the decoction required to produce the dis- 

 ease, the poison must be weak, or, if strong, it must be in very 

 small amount. 



SCIENTIFIC NEWS IN WASHINGTON. 

 Effect of Permanent Moisture on Certain Forest-Trees. 1 



In 1874, while engaged in the work of the Kentucky Geological 

 Survey in the lowland district near the Mississippi, I had an oppor- 

 tunity of making some inquiries concerning the knees of the swamp 

 cypress, which led me to the supposition that these peculiar processes 

 from the roots served in some manner to aerate the sap. Their 

 functional importance was indicated by the fact that whenever their 

 summits were covered by water, as by the sinking of the ground on 

 which they stood in the earthquake of 181 1, or by the artificial ele- 

 vation of the water during the summer season in mill-ponds, the 

 trees to which they belonged inevitably died. On the other hand, 

 the trees which grew upon high ground failed to develop any knee 

 processes beyond slight tuberosities on the upper side of their main 

 roots. The results of this and other inquiries were put in press 

 about twelve years ago, but were first published in Vol. XVI. No. I, 

 of the " Memoirs of the Museum of Comparative Zoology at Har- 

 vard College," June, 1887. An incidental reference to the fact was 

 made in the third volume of the reports of progress of the Ken- 

 tucky Geological Survey (1877), p. 74. 



Since that time I have incidentally observed certain other phe- 

 nomena connected with the conditions of our forest-trees in swamps, 

 which, so far as my knowledge goes, have not received adequate 

 attention. I have hoped to find an opportunity to make a more 

 careful inquiry into the subject, but this does not seem possible. I 

 therefore venture to give the results of the very incomplete investi- 

 gation in this letter. 



As it seemed unlikely that the cypress should be the only tree to 

 develop root processes intended to fit the plant for semi-aquatic 

 Ufe, I searched for similar excrescences on the roots of our other 

 forest-trees which find their station in wet lands. Until within a few 

 months, I have been unable to find any other species in which the 

 processes were sufficiently developed to be classed in importance 

 with the cypress knees. I A very little inquiry showed me that all 

 trees which find a station in very wet lands have their large roots 

 nearer the surface of the soil than in the upland districts, and sev- 

 eral species exhibit a tendency to have their roots at certain points 

 actually on or above the soil. Observations in the Mississippi 

 swamps seem to show that our ordinary tupelo or sour gum {Nyssa 

 uniflora, Walt.) exhibited rather more of this tendency than any 

 other species, and I suspected that under favorable circumstances 

 it might show a peculiar adaptation to its swampy surroundings. 

 Observations in the Mississippi valley were difficult, for the reason 

 that the pools beneath which the roots of the trees extend dry out 

 during the summer droughts. Recently, however, in the Dismal 

 Swamp district of Virginia and North Carolina, I found many areas 

 occupied by the tupelo which did not become desiccated in the dry 

 seasons. In all such positions, the tree, when of mature growth, 

 has a peculiar feature in its roots which serves in an admirable way 

 to accomplish the results attained by the cypress knees, though the 

 method by which it is attained is peculiar. In place of forming a 

 spur-like process upon the root, the root itself arches upward in 

 such a manner that the upper part of the bow rises above the level 

 of the water in the growing season. Where the depth of water is 

 slight, the arch may be indistinctly developed. Where the water 

 stands a foot or more in depth, the arch becomes very much ele- 

 vated. I found specimens in which the roots assumed a horseshoe- 

 like curve, rising to the altitude of three feet above the soil, the 

 distance apart of the roots at their base not exceeding a foot. 

 These roots commonly have a diameter of from three to six 

 inches. The fact that they rise above the level of the water in the 

 growing season is often attested by a considerable growth of an- 

 nual plants which have become planted in the crevices of the bark. 

 These roots of the Nyssa do not appear to develop their arches 

 until the tree attains a considerable size. I found no trace of them 



' Preliminary notice of some results of the United States Geological Surrey ex- 

 amination of swamp-lands, by N. S. Shaler. 



