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THE POPULAR SCIENCE MONTHLY. 



suddenly disturbed. The hive was now 

 placed on the hive-board, with the entrance 

 toward the bees. For a little while they 

 continued to run about, as if bewildered, 

 but then was heard a peculiar vibrating and 

 buzzing sound proceeding from the hive. 

 In an instant all the bees faced about, with 

 their heads toward the hive, and all marched 

 into it in regular procession. 



A New Respirator. A new mask for fil- 

 tering dust out of the atmosphere, and in- 

 tended for use by workmen who follow 

 sundry unhealthy trades, has been devised 

 by Dr. B. W. Richardson. Having tried 

 various substances in order to find a good 

 filter, he gives the preference to feathers. 

 The advantages of feathers as filters of 

 dust are many : they are light, they sepa- 

 rate perfectly, admitting air in any quantity 

 while excluding dust, and they absorb water 

 less perhaps than any other porous flexible 

 substance. They have the further advan- 

 tage of being cheap, and of being easily 

 made up into filters. In constructing his 

 mask he connects the light feathers drawn 

 from the leg-plumage of the pheasant along 

 a line of tape. This band he wraps around 

 the perforated breathing-tube of the mask, 

 so that the feathers fall over the perfora- 

 tions. In inspiration the feathers come 

 down over the perforations, filtering the air 

 as it enters, while in expiration they are 

 blown out from the tube as feather-valves. 



Bat-GnailO. In reply to a circular of 

 inquiry addressed to numerous correspond- 

 ents in the Southern States, Mr. McMur- 

 trie, chemist to the United States Depart- 

 ment of Agriculture, received a number of 

 letters describing deposits of " bat-guano." 

 Near Georgetown, Williamson County, Tex- 

 as, there is a deposit supposed to amount 

 to hundreds of tons, many apartments in 

 the cave in which the excrement is found 

 being filled to the mouth. Near Tuscumbia, 

 Alabama, is a deposit estimated to be worth 

 $20,000. A cave near San Antonio, Texas, 

 is supposed to contain 15,000 or 20,000 

 tons of this guano, and the store is an- 

 nually increasing. Samples from these and 

 other deposits have been analyzed by Mr. 

 McMurtrie. Most of them he found to 

 contain both ammonia and nitrates. Un- 



der the microscope the material is seen 

 to consist of the remains of the hard parts 

 of insects in a finely-comminuted condition, 

 which are the source of its nitrogenous 

 constituents. As a fertilizer this guano 

 compares favorably with the fish-products 

 manufactured in New England, and even 

 with Peruvian guano. 



Prof. Marsh and his Paleontologteal 

 Work. Prof. O. C. Marsh, in a lecture to 

 the graduating class of Yale College, 

 summed up the main results of his paleon- 

 tological researches in the Rocky Mountains. 

 A syllabus of the lecture is published in the 

 American Journal of Science. His conclu- 

 sions as to the size and growth of the brain 

 in mammals, from the beginning of the 

 Tertiary to the present time, may be briefly 

 stated thus: 1. All tertiary mammals had 

 small brains. 2. There was a gradual in- 

 crease in the size of the brain during this 

 period. 3. This increase was mainly con- 

 fined to the cerebral hemispheres. 4. In 

 some groups the convolutions of the braia 

 have gradually become more complicated. 

 5. In some the cerebellum and olfactory 

 lobes have even diminished in size. There 

 is some evidence that the same law of 

 brain-growth holds good for birds and rep- 

 tiles from the Cretaceous to the present 

 time. Some additional conclusions in re- 

 gard to American tertiary mammals as far 

 as now known are as follows: 1. All the 

 ungulata from the eocene and miocene had 

 upper and lower incisors. 2. All eocene 

 and miocene mammals had separate sca- 

 phoid and lunar bones. 3. All mammals 

 from these formations had separate meta- 

 podial bones. At the conclusion of the 

 lecture Prof. Marsh announced that his 

 work in the field was essentially completed, 

 and that all the fossil remains collected and 

 in part described were now in the Yale Col- 

 lege Museum. In future he should devote 

 himself to their study and full description, 

 and he hoped at no distant day to make 

 public the complete results. 



Seed-Production of the Sngar-Beet. 



From experiments made by Corenwinder, it 

 appears that when beet-roots are planted 

 for the sake of seed, they, on first sprout- 

 ing, part with a certain quantity of their 



