240 



THE AMERICAN MONTHLY 



[Dec, 1882. 



amoeba. But view this with a high power 

 of the microscope, and at once it will be 

 seen that it is not a perfectly homogeneous 

 mass of matter. Throughout its substance 

 there will be seen minute granules which 

 seem to lie free in the more fluid portion, 

 but which are not uniformly distributed 

 through it. At some period of its life, it 

 is probable that every amoeba possesses a 

 nucleus, — the function of which it is not 

 possible to explain, but is supposed to be 

 a portion of the protoplasm more highly 

 organized than the rest. Advancing 

 higher among the species we find a con- 

 tractile vesicle, a clear circular spot or 

 cavity in the protoplasm, which pulsates 

 in a regular manner, as though -it were 

 alternately filled and emptied of a watery 

 fluid. 



Among the simplest and most minute 

 forms, no definite external envelope can 

 be discerned, but as we pass from these 

 upward in the scale of development a 

 thickening of the outer protoplasm is ob- 

 served, which gradually becomes more and 

 more pronounced until a well-defined en- 

 closing membrane is found among all the 

 more highly developed species. He then 

 gave an account of the structure of the 

 Radiolaria, their mode of growth, their 

 food and methods of reproduction, and 

 finally referred to the part they have taken 

 in the formation of rocks. At Barbadoes 

 their remains are found forming rock 1,100 

 feet in thickness, and at the Nicobar 

 Islands, 2,000 feet. 



Mr. Britton showed some Radiolaria 

 dredged from 3,000 fathoms. 



Mr. Balen showed some rotifers living 

 within the sphere of Volvox globator. 



NOTICES OF BOOKS. 



A Sketch of the Progress of American 

 Mineralogy. An adress delivered be- 

 fore the American Association for the 

 Advancement of Science, at Montreal, 

 August 23d, 1882. By Professor Geo. 

 J. Brush, President. (Pamphlet, pp.42.) 



Ninth Annual Report Relating to the 

 Registry and Return of Births, Mar- 

 riages attd Deaths in Michigan for 

 the year i8-/§. By the Superintendent 

 of Vital Statistics, under the general 

 direction of the Secretary- of State of 

 the State of Michigan. By authority. 

 Lansing: W. E. George & Co., State 

 printers and binders, 1881. (Pp. 339.) 



Tenth An?iual Report Relating to the 

 Registry and Return of Births, Mar- 

 riages and Deaths in Michigan for 

 the year i8y6. By the Superintendent 

 of Vital Statistics, under the general di- 

 rection of the Secretary of State of the 

 State of Michigan. By authority. Lan- 

 sing : W. S. George & Co., State print- 

 ers and binders, 1881. (Pp. 331.) 

 The compilation of these valuable books 

 has involved an amount of labor which 

 few persons can well appreciate until they 

 make a study of the statistical tables. 

 Yet the importance of the work cannot 

 be over estimated, since it must lead to a 

 better understanding of the laws which 

 affect human health and happiness. It is 

 to be regretted that all the States are not 

 compiling annual statistics as carefully as 

 the State of Michigan. 



A Co7itribution to the Study of the Bac- 

 terial Organisms Cofnmonly Found 

 upon Exposed Mucous Surfaces and 

 in the Alimentary Canal of Healthy 

 Individuals. Illustrated by photomi- 

 crographs. By George M. Sternberg, 

 Surgeon U. S. Army, etc. (Pamphlet, 

 pp. 26, three plates.) 



This is a valuable contribution, the sub- 

 ject of which is fully expressed by the title. 

 It was read at the Cincinnati meeting 

 of the A. A. A. S. last year. The plates 

 illustrate two forms of apparatus used in 

 culture-experiments, and a number of 

 forms of bacteria found upon various mu- 

 cous surfaces. The plates are by the 

 heliotype process. 



Exchanges. 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted 

 objects, and material for mounting.] 



Wanted — To exchange, good slides correctly 

 named, or material for mounting for same. — F. C. 

 Smith, Bridgeport, Conn. 



Wanted — Diatomaceous material from New Hamp- 

 shire containing , -J ;«//izj#/4';<?-a Lindheitneri, in ex- 

 change for materials from North of Ireland. — William 

 A. Firth, Whiterock, Belfast, Ireland. 



Siriatella u?iipuncta, Rhabdonenia Adriaticum, 

 and other first-class crude material, to exchange for 

 named diatoms and first-class material — prepared and 

 particularly foreign material preferred. — M. A. Booth, 

 L(*igmeadow, Mass. 



Wanted — Animal parasites, Ixodes, Acari, etc., 

 either mounted or unmounted. — W. A. Hyslop, 22 

 Palmerston Place, Edinburg, Scotland. 



