58 The Microscope. 



Mr. Thos. Christian, the discoverer of the diatom Raphido- 

 discus Christianii, has sent us a fine photograph of this interesting 

 object, which is said to be the missing link in the structure of 

 diatoms. R. Christianii is disk form, having a navicula centre, 

 meridian line and nodules. Mr. Christian will soon give the history, 

 etc., of the discoveiy, and a description of this diatom, in The 

 Microscope — for which we bespeak many interested readers. 



Mr. ScHERMERHORN, President of the Iowa State Dairyman's 

 Association, and himself one of the largest dealers in dairy produce 

 in that State, has recently interested himself in the question of 

 butter tests. In the Iowa State Register of Jan. 10th., he says : — 



" In view of the fact that the reliability of butter tests has 

 been brought into question, I furnished to Dr. A. G. Field, of this 

 city, eight packages of butter and mixtures, for microscopical test- 

 ing. They consisted of various mixtures of lard, salt and butter, 

 butterine, and also pure butter of various ages and modes of manu- 

 facture. With the exception of one package of genuine butter, 

 four years old, they all had the appearance of good butter. They 

 were numbered, and the composition of each recorded, but of 

 which Dr. Field knew nothing before making the examination. In 

 every case his report was correct. He stated that he followed the 

 method of Dr. Thomas Taylor, of AVashington, D. C, relying 

 principally upon the form of crystal and the use of polarized light." 



This additional testimony to the reliability of Dr. Taylor's 

 msthods, coming from a State where butter-making is an important 

 industry, bears with it great weight. 



In reply to many inquiries as to the location of Gray's Ferry 

 Road, we quote from a letter of Dr. George A. Koenig: " The locality 

 was opened by a cut of the new Baltimore & Ohio R. R., and is 

 now quite inaccessible, since the cut is throughout lined by a wall, 

 and the bed comes nowhere to an outcrop. Gray's Ferry is on 

 the Schuylkill, within the City of Philadelphia." See "News and 

 Notes," Oct., 1886, p. 238. 



BOOK REVIEWS. 



"TuRouGH A Microscope." By Samuel Wells, Mary Treat, and F. L. Sargent, 

 pp. 126. The Inter-State Publishing Co., Boston and Chicago; D. O. 

 Haynes & Co., Detroit. 



In a first-book of microscopy, the beginner should find the 

 plainest instruction, couched in the simplest language — the very 

 A B C of the subject. Such a book immediately finds favor 

 Avith the many, and does a service which is both satisfactory and 



