74 



THE AMERICAN MONTHLY 



[April, 



Trichinae in Lard. — There are 

 strange rumors running through the 

 newspapers of this city, about Trich- 

 inae that have been found in lard. 

 The Herald Xxz.cQ'-, them to the author- 

 ity of the same gentleman who has 

 generously informed the public, 

 through the columns of his own paper, 

 that our Figure 9, printed last month, 

 was a " wretched misrepresentation 

 of free trichinae." Now, we are will- 

 ing to admit that our illustration is 

 not quite perfect, but really we think 

 the fault was not ours, since the 

 cut was not engraved for this Jour- 

 nal. At the same time, we believe 

 that it represents trichinae better than 

 does any thing that can be discovered 

 in lard. 



Fungi and Contagion. — The 

 article we publish this month from Dr. 

 Salmon, who may well be regarded 

 as one of our best authorities upon 

 the subject which he treats, is the 

 first of a series which he has promised 

 to furnish for this Journal. We are 

 pleased to have such an excellent op- 

 portunity to present this confusing sub- 

 ject in a manner that will make it in- 

 teresting and intelligible. The editor- 

 ial comments to which the author al- 

 ludes, and which have generally been 

 adverse to the germ-theory, have been 

 more especially directed against the 

 unscientific and inconclusive charac- 

 ter of most of the investigations, the 

 greater number of which have been 

 conducted by persons who were not 

 qualified to carry on scientific research 

 of such an extremely delicate nature. 



~o- 



Protococcus Nivalis. — Mr. Eug. 

 Mauler, of Switzerland, in response to 

 a letter, has given us some interesting 

 facts concerning this little-studied 

 plant, the cause of the red-snow. It 

 is only found within the limits of the 

 eternal snows of the Alps, at a very 

 great height, and is always associated 

 with P. viridis. M. Mauler regards the 

 red and the green cells as only dif- 

 ferent conditions of the same plant. 



but the transformation takes place 

 very slowly, requiring a whole year. 

 In the preparations of this alga that 

 M. Mauler has kindly sent us, there 

 are many spherical cells that were 

 once of a bright-green color, no doubt, 

 and an occasional smaller cell of a 

 bright-red color, which is the P. ni- 

 valis. The green cells greatly pre- 

 ponderate in the specimens. 



Micrometers. — Prof. W. A. Ro- 

 gers, of Cambridge, has at last com- 

 pleted -his new dividing engine. 

 This machine has been constructed 

 at the works of the Waltham Watch 

 Factory, under the personal super- 

 vision of the Mechanical Superinten- 

 dent, Mr. Chas. V. Woerd, who has 

 arranged all of its details. The con- 

 struction has consumed three years, 

 and the cost has been about $4,500. 



The Waltham Watch Co. does not 

 undertake to make dividing engines, 

 but in this case the necessity for 

 perfect workmanship was imperative, 

 and upon the representation that it 

 was undertaken in the interest of a 

 useful scientific investigation, the 

 Manager, Mr. R. E. Robbins, kindly 

 consented to afford accommodations 

 for its construction. 



The extreme working length of the 

 screw is half a metre. The theoreti- 

 cal limit of subdivision is about two 

 billionths of a centimetre. The 

 practical limit may be set at about 

 one fifty-thousandth of a centimetre. 



It is yet too early to say whether 

 this machine will do all that is claimed 

 for it ; but Professor Rogers invites 

 investigation, and, as we understand 

 the matter, he is willing to furnish 

 standards without cost, to any com- 

 petent person who will make a careful 

 study of the subdivisions, and who 

 will at the same time agree to publish 

 the results, without communication 

 with him. 



In order to meet a small portion 

 of the expense incurred in the con- 

 struction of the machine. Professor 

 Rogers will, upon application, make 

 standard micrometers, guaranteed to 



