224 



THE AMERICAN MONTHLY 



[December, 



quite lost, only a faint tinge of red 

 remaining. Tiie diameter of these 

 cells ranges from xo.8//. to 30;/. 



A specimen was received in Janu- 

 ary of this year from Poverty Gulch, 

 Colorado, sent by Mr. Alexander 

 McDougall. It is numbered in the 

 museum register 74,537. 



From the letter which accompanied 

 this specimen I quote as follows : — 



' Sediment of a small quantity of 

 snow gathered in Poverty Gulch, 

 Crested Butte Co., Colorado, at an 

 altitude of 12,000 feet, on the i6th of 

 September, 1S84. The snow-fall of 

 1883-4 '^^s very unusual, proving a 

 great barrier to mining operations in 

 this district. In the spring of 1884 

 the uplands and valleys that were 

 still covered with snow presented 

 quite a novel appearance, the red and 

 white blended together in beautiful 

 harmony. What it was or whence 

 it came was quite a mystery to the 

 miners, and in hopes that you will 

 elucidate the mystery I take the 

 liberty of sending you a small quantity. 



' The snow-ball that yielded this 

 sediment was gathered from snow 

 that was about six feet in depth. It 

 changed its color to brown, but by 

 wetting a few grains and rubbing on 

 white paper it is red.' 



I made a few observations on this 

 specimen, and attempted to cultivate 

 some of the cells, but without success. 

 The cells were of a bright red color, 

 sometimes apparently quite naked, 

 but frequently enclosed singly, or 

 three or more together, in a colorless, 

 shrivelled envelope. The cells, ex- 

 clusive of the outer envelope, meas- 

 ured from 14.3'/ to 29.2// in diameter. 

 Occasionally small naked cells were 

 observed only 6.5,'/. in diameter. 



The contents of perfect and fresh 

 cells appears to be quite clear and 

 transparent, with occasionally a well- 

 defined sort of vesicle of a deeper 

 color than the rest. 



When the endochrome was pressed 

 out from the cells into the surround- 

 ing water, it contracted in spherical, 

 oil-like masses. 



The surrounding envelope is quite 

 hard, tough, and resisting. 

 o 



Photo-Micrography. — II. 



BY THE EDITOR. 



2. Apparatus. 



We have deemed it advisable to 

 reverse the intended order of the sub- 

 heads of this di^'ision of the subject, 

 that we may have opportimity to test 

 a form of apparatus which we desire 

 to describe in this connection should 

 it prove satisfactory. We will there- 

 fore defer the description of micro- 

 scope and camera until next month, 

 taking up now 



a. Plates^ Chemicals^ Devel- 

 oping Apparatus., Dark- 

 room., etc. 



Plates. — It is not our province to 

 advocate the use of any particular 

 band of plates, since all the large 

 manufacturers doubtless furnish good 

 plates. The kind best adapted to 

 photo-micrography is a moderately 

 quick plate that works clear. A plate 

 that yields a negative covered with a 

 general fog, such as some of the more 

 rapid ones are apt to show, is not to 

 be recommended. It must not be 

 inferred, however, that extremely 

 rapid plates cannot be found that 

 work perfectly clear. Some makers, 

 in attempting to excel in the sensi- 

 tiveness of their emulsions, go so far 

 that a very slight forcing in the de- 

 velopment causes a noticeable gen- 

 eral fog over the plates. The advan- 

 tage of extreme rapidity obtained at 

 the expense of clearness in the shad- 

 ows, is, to say the least, questionable. 

 So long as the plate works clear, its 

 rapidity is a secondary consideration. 

 Doubtless a moderately rapid plate 

 will be most generally preferred for 

 work with powers up to a Jg-inch, 

 and quicker plates for higher powers. 



Developing Apparatus. — The ne- 

 cessary apparatus, which should be 

 purchased at the beginning, is the 

 same as would be required for field 

 work. We give a list of the articles, 

 with the current prices appended : — 



