220 



THE AMEKICAN MONTHLY. 



[November. 



— Mr. W. P. Collins has issued his ' Cat- 

 alogue of scientific books, mostly second- 

 hand,' No. 13, 1885, which includes a 

 long list of books on microscopical sub- 

 jects, many of which are rare. In this 

 connection we may also call attention to 

 the slides of insects prepared by Mr. 

 Chas. Collins, Jr., which are sold in sets 

 of one dozen for half a guinea. These 

 are mounted without pressure, and are 

 highly spoken of. 



CORRESPONDENCE. 



An Unknown Plant. 



To THE Editor: — A short time ago 

 Mr. Wolle kindly sent me a small vial of 

 desmidaceous material, and in looking 

 over it lately I have discovered a curious 

 little alga, which I cannot make out. I 

 send a sketch of it. I have looked over 

 all works available likely to throw any 

 light on it, but can find no drawing or 

 mention of anything like it. It is very 

 minute, the sketch being drawn under 

 about X 680. What can it be ? Can any 

 readers of your Journal kindly say ? 

 E. H. Wagstaff. 



Birmingham, England. 



[The sketch enclosed by our corre- 

 spondent was sent to Mr. Wolle, who was 

 unable to identify it without further in- 

 formation. The color should have been 

 stated, as it is an essential character. If 

 green the plant might be a fruiting fila- 

 ment of Cylindrocapsa graminclla, Wolle ; 

 if ajruginous, which is more likely, it 

 mightbe asporiferous ^■Axn^xv^oiAnabcna. 

 As the determination is uncertain, the 

 sketch is not reproduced. — Ed.] 



o 



Parasite of a Grasshopper. 



To the Editor : — The worm taken 

 from the grasshopper by Mr. E. G. Day 

 was probably Mermis albicans, a hair- 

 worm parasitic upon grasshoppers, etc. 

 It sometimes grows to the length of thirty 

 inches before quitting its host. Mr. Day 

 will find the life-history of his capture in 

 The First Annual Report of the United 

 States Entomological Commission, p. 326, 

 etseq. 



D. N. DE Tarr. 



Boone, Iowa. 



White Zinc for Mounting. 

 To THE Editor : — In looking over 

 some sixty slides withdrawn from circu- 

 lation and placed in the reference cabinet 

 of the American Postal Microscopical 

 Club, I found that 27 of the preparations 



had been sealed with the celebrated zinc 

 white cement. 



Of these 27 slides, 21 required re-ce- 

 menting, and in every case the cement 

 was so brittle that it needed but a touch 

 of the knife-blade to cause the fragments 

 which remained to leave the glass. I am 

 perfectly well aware that circulation for a 

 year or more through the circuits of the 

 club is a very severe test for a cement, 

 and I do not doubt that many of the slides 

 would have been in better condition if, 

 during the same length of time they were 

 travelling about the country in the boxes 

 of the club, they had, instead, been lying 

 secure in a cabinet. But it is a notable 

 fact that every other cement used seems 

 to have stood the trial better than the zinc 

 white. I have excluded from considera- 

 tion in every case slides that were broken 

 or in any way injured in the mails. The 

 other cements used were chiefly shel-lac, 

 Brunswick-black, and a brown cement 

 which looks like marine glue. These 

 have all seemed to stand well. I had to 

 repair but one shel-lac ring out of some 

 eighteen specimens. If you wish to pub- 

 lish these facts for the benefit of the read- 

 ers of your Journal you have my consent 

 to do so. You have spoken in the Jour- 

 nal once or twice about this cement, 

 warning microscopists not to rely too 

 much upon its supposed virtues, and it 

 was this fact that caused me to think that 

 you might value the facts given above. 

 C. E. Hanaman. 



Troy, N. Y. 



NOTICES OF BOOKS. 



Diatomaceerna i Kutzings exsikkatverk : 

 Algarutn agues dulcis Germanicarum 

 Decadco. Af N. G. Lagerstedt. Ofver- 

 sight af Kongl. Vetensk aps-Akade- 

 miens Forhandlingar, 1884. No. 2. 

 Stockholm. (Pamphlet, pp. 35, with i 

 plate.); 

 The s'pE2cies are described in Latin, and 



the synoTiyme is quite fully given for each 



one. 



Exchanges, 



[Exchanges are inserted in this column without 

 charge. They will be strictly limited to mounted ob- 

 jects, and material for mounting.] 



Fossil Diatomaceous Earth, (a new find), very inter- 

 esting forms for other material. 



J. walker, 



, 810 Twelfth Ave., South Minneapolis, Minn. 



Wm. R. Mandeville, M. D., of New Orleans, La., 

 483 Magazine street, has for exchange or sale a num- 

 ber of firsL-class mounts of pathological specimens, in- 

 cluding yellow fever and leprosy ; also a large number 

 of miscellaneous objects. 



