DECEBfBEB 1, 1897.] 



KNOWLEDGE. 



297 



Ice-floes and floating timber do much damage to the 

 lodges, and thus entail an annual repair, which, aa already 

 said, is carried out in autumn. Spring and autumn floods 

 also frequently submerge the lodges, from which large 

 portions are loosened and swept away. From twenty to 

 thirty years is the probable period during which a lodge 

 is habitable. 



On the bank of the river in the neighbourhood of the 

 lodge numerous burrows are to be met with, a few of 

 which are in connection with the former, although most 

 are entirely separate. Burrows are the first refuges formed 

 by the beaver when taking possession of a fresh spot, and 

 they may accordingly be likened to the rude sheds erected 

 by workmen employed on building a mansion. Probably 

 each lodge is tenanted only by a single couple and their 

 young family ; the young beavers, when able to do without 

 parental assistance, either settling down temporarily in 

 burrows in the immediate neighbourhood, or wandering 

 away to found new colonies. Small lodges constructed in 





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m 





y^'i\ 



T r ^^ 



:'l?^lS- ^ 



:J^K 



Aspen (Popiilus tremula) felled by the Beaver (Aamli). 



a kind of jerry-building fashion appear to be run up by 

 bachelor beavers who have not yet ventured to take upon 

 themselves the responsibilities of a wife and family. There 

 may, however, be also spinster beavers to whom such 

 accommodation is also necessary — it is to be hoped only 

 temporarily. 



Dams are constructed where beavers have quartered 

 themselves by the sides of gently flowing streamlets, or 

 small posts through which a current rans, in order to 

 obtain water of sufficient depth and maintaining a constant 

 level. The " bund " is substantially buUt and difficult to 

 demolish. One examined in 189.3 was constructed at the 

 outflow of a small stream through a forest marsh ; and 

 where there wis formerly but a small shallow pool, a pond 

 or lake of some few hundred yards in diameter soon 

 resulted from the labours of these indefatigable rodents. 

 The "bund," which was about fifteen feet in length, with 

 a cross section of some two feet, was entirely made in the 

 course of three weeks during the summer of 1890. la 

 Canada, when the dam is sufficiently stout, the pool will 

 eventually silt up and form a " beaver-meadow,'' but Mr. 

 Collett does not record any of these " meadows " in 

 Norway. 



During the cold winter months the beavers, although 

 not hibernating in the proper sense of the term, pass what 

 appears a somewhat dull existence in the central chamber 

 of the lodge, the roof of which for most of the time is 

 buried in snow. Sometimes, however, when the weather 

 is mild for the season, and an unusually cold autumn 

 prevented the completion of the annual repairs at the 

 proper time, the beaver will venture out from their retire- 

 ment for a short period in order to remedy such dilapida- 

 tions as stand in urgent need of immediate attention. 

 When they have been engaged on such works their foot- 

 prints are visible in the snow. Immediately after the 

 breaking up of the ice in spring the animals issue forth to 

 procure a fresh supply of food and resume their daily 

 avocations. 



The young beavers are born in April or May, three being 

 apparently a common number in a litter. At first their 

 eyes are closed, but they grow rapidly, and by September 

 or October are about the size of a cat. When able to shift 

 for themselves they leave the parental lodge, and fre- 

 quently start oft' to found a family in some fresh locality, 

 L Ithough sometimes they set oii' on their wanderings alone. 

 Following the courses of smill streams, they frequently 

 tack straight across the open mountain slopss for miny 

 miles, so that one or more not unfrequently make their 

 appearance in valleys where none have been known for 

 years. They will even ocjasionally cross small arms of 

 the sea ; and the perils of the journey end in death to no 

 inconsiderable number. 



Several old-time superstitions still cling round the 

 beaver. One of the most persistent and most incorrect is 

 that the flat sealy tail is employed as a trowel for plastering 

 down the mud during building operations. Another is 

 that the secretion of the tail glands — the c<ftoreum of the 

 old phavmacopcijia — has the property of frightening away 

 whales or porpoises when approaching a boat I Still 

 more strange is the old idea that some individuals were 

 compelled to lie on their backs and be laden with building 

 materials, when they were dragged by their companions to 

 the scene of operations. Probably this fable originated 

 from the circumstance that many individuals have tUe hair 

 worn oft" the back from constantly passing up and down 

 the narrow burrow or entrance to a lodge. 



NoticfS of Boolts. 



# — ■ 



Botanical Microtechnique. By Dr. A. Zimmermann. 

 Translated from the German by James Ellis Humphrey, 

 S.D. (Archibald Constable i Co.) By the publication 

 of an English edition of Dr. Zimmermann's work, a most 

 excellent treatise on a subject of wide interest is placed 

 within the reach of students. Books already existing on 

 the same subject are wanting in directions that are a dis- 

 tinguishing feature of the present volume. Although of 

 necessity it must be a compilation from various original 

 papers and text-books, it is not an unsystematic collection 

 of formubi'. The methods of dealing with each component 

 part of a plant are prefaced by a description of the chemical 

 composition and structure of these parts. The intelligent 

 student, working at any given process, has thus the neces- 

 sary data at his disposal to appreciate the reaction that 

 takes place, and to try possible variations and improve- 

 ments. There is a short but useful chapter on staining 

 bacteria, and the numerous references comprise all the 

 recent literature of value. The book can be recommended 

 as a complete and well-arranged treatise on a subject of 

 considerable importance. 



In Russet Mantle Clad. By George Morley. (Skeffington 

 & Co.) Illustrated. lOs. 6d. Mr. Morley dedicates hie 



